diff --git a/pybtc/connector/utxo.py b/pybtc/connector/utxo.py
index db102cb..3fe92d6 100644
--- a/pybtc/connector/utxo.py
+++ b/pybtc/connector/utxo.py
@@ -19,8 +19,7 @@ class UTXO():
         self.clear_tail = False
         self.last_saved_block = 0
         self.last_cached_block = 0
-        self.save_future = asyncio.Future()
-        self.save_future.set_result(True)
+        self.save_process = False
         self.load_utxo_future = asyncio.Future()
         self.load_utxo_future.set_result(True)
         self._requests = 0
@@ -60,71 +59,83 @@ class UTXO():
         # save to db tail from cache
         self.log.critical("save utxo>>>>")
         return
-        if not self.save_future.done():
-            await self.save_future.done()
+        if  self.save_process or not self.cached:
             return
-        self.save_future = asyncio.Future()
-        while True:
-            c = len(self.cached) - self._cache_soft_limit - self.block_txo_max
-            if c <= 0: break
-            self.log.critical("str>>>>")
-            try:
-                lb = 0
-                for key in iter(self.cached):
-                    i = self.cached[key]
-                    if c>0 and (i[0] >> 42) <= block_height:
-                        c -= 1
-                        lb = i[0] >> 42
-                        continue
-                    break
+        self.save_process = True
+        try:
+            lb = 0
+            block_changed = False
+            utxo = set()
+            while self.cached:
+                i = self.cached.pop()
+                if lb != i[1][0] >> 42:
+                    block_changed = True
+                    lb = i[1][0] >> 42
+                if self.cached <= self.size_limit:
+                    if block_changed:
+                        break
+                utxo.add((i[0],b"".join((int_to_c_int(i[1][0]),
+                                         int_to_c_int(i[1][1]),
+                                         i[1][2]))))
+                if block_changed:
+                    self.cached.append({i[0]: i[1]})
 
-                if lb:
-                    d = set()
-                    for key in range(self.last_saved_block + 1, lb + 1):
-                        try:
-                            [d.add(i) for i in self.deleted[key]]
-                        except:
-                            pass
+            #
+            #     block_height
+            # for key in iter(self.cached):
+            #     i = self.cached[key]
+            #     if c>0 and (i[0] >> 42) <= block_height:
+            #         c -= 1
+            #         lb = i[0] >> 42
+            #         continue
+            #     break
+            #
+            # if lb:
+            #     d = set()
+            #     for key in range(self.last_saved_block + 1, lb + 1):
+            #         try:
+            #             [d.add(i) for i in self.deleted[key]]
+            #         except:
+            #             pass
+            #
+            #     a = set()
+            #     for key in iter(self.cached):
+            #         i = self.cached[key]
+            #         if (i[0] >> 42) > lb: break
+            #         a.add((key,b"".join((int_to_c_int(i[0]),
+            #                               int_to_c_int(i[1]),
+            #                               i[2]))))
 
-                    a = set()
-                    for key in iter(self.cached):
-                        i = self.cached[key]
-                        if (i[0] >> 42) > lb: break
-                        a.add((key,b"".join((int_to_c_int(i[0]),
-                                              int_to_c_int(i[1]),
-                                              i[2]))))
+            # insert to db
+            d = set()
+            async with self._db_pool.acquire() as conn:
+                async with conn.transaction():
+                    if d:
+                        await conn.execute("DELETE FROM connector_utxo WHERE "
+                                           "outpoint = ANY($1);", d)
+                    if a:
+                        await conn.copy_records_to_table('connector_utxo',
+                                                         columns=["outpoint", "data"], records=utxo)
+                    await conn.execute("UPDATE connector_utxo_state SET value = $1 "
+                                       "WHERE name = 'last_block';", lb)
+            self.saved_utxo += len(utxo)
+            self.deleted_utxo += len(d)
 
-                    # insert to db
-                    async with self._db_pool.acquire() as conn:
-                        async with conn.transaction():
-                            if d:
-                                await conn.execute("DELETE FROM connector_utxo WHERE "
-                                                   "outpoint = ANY($1);", d)
-                            if a:
-                                await conn.copy_records_to_table('connector_utxo',
-                                                                 columns=["outpoint", "data"], records=a)
-                            await conn.execute("UPDATE connector_utxo_state SET value = $1 "
-                                               "WHERE name = 'last_block';", lb)
-                            await conn.execute("UPDATE connector_utxo_state SET value = $1 "
-                                               "WHERE name = 'last_cached_block';", block_height)
-                    self.saved_utxo += len(a)
-                    self.deleted_utxo += len(d)
-
-                    # remove from cache
-                    for key in a:
-                        try:
-                            self.cached.pop(key[0])
-                        except:
-                            pass
-
-                    for key in range(self.last_saved_block + 1, lb + 1):
-                        try:
-                            self.deleted.pop(key)
-                        except:
-                            pass
-                    self.last_saved_block = lb
-            finally:
-                self.save_future = False
+            # # remove from cache
+            # for key in a:
+            #     try:
+            #         self.cached.pop(key[0])
+            #     except:
+            #         pass
+            #
+            # for key in range(self.last_saved_block + 1, lb + 1):
+            #     try:
+            #         self.deleted.pop(key)
+            #     except:
+            #         pass
+            self.last_saved_block = lb
+        finally:
+            self.save_future = False
 
     def get(self, key):
         self._requests += 1