diff --git a/internal/caches/storage_memory.go b/internal/caches/storage_memory.go
index ce2cca0..cd446c6 100644
--- a/internal/caches/storage_memory.go
+++ b/internal/caches/storage_memory.go
@@ -584,13 +584,19 @@ func (this *MemoryStorage) flushItem(key string) {
 }
 
 func (this *MemoryStorage) memoryCapacityBytes() int64 {
+	var maxSystemBytes = int64(utils.SystemMemoryBytes()) / 3 // 1/3 of the system memory
+
 	if this.policy == nil {
-		return 0
+		return maxSystemBytes
 	}
 
 	if SharedManager.MaxMemoryCapacity != nil {
 		var capacityBytes = SharedManager.MaxMemoryCapacity.Bytes()
 		if capacityBytes > 0 {
+			if capacityBytes > maxSystemBytes {
+				return maxSystemBytes
+			}
+
 			return capacityBytes
 		}
 	}
@@ -599,17 +605,15 @@ func (this *MemoryStorage) memoryCapacityBytes() int64 {
 	if capacity != nil {
 		var capacityBytes = capacity.Bytes()
 		if capacityBytes > 0 {
+			if capacityBytes > maxSystemBytes {
+				return maxSystemBytes
+			}
 			return capacityBytes
 		}
 	}
 
-	// half of the system memory
-	var memoryGB = utils.SystemMemoryGB()
-	if memoryGB < 1 {
-		memoryGB = 1
-	}
-
-	return int64(memoryGB) << 30 / 2
+	// 1/4 of the system memory
+	return maxSystemBytes
 }
 
 func (this *MemoryStorage) deleteWithoutLocker(key string) error {
diff --git a/internal/utils/system.go b/internal/utils/system.go
index aec07e5..9d69967 100644
--- a/internal/utils/system.go
+++ b/internal/utils/system.go
@@ -8,6 +8,7 @@ import (
 )
 
 var systemTotalMemory = -1
+var systemMemoryBytes uint64
 
 func init() {
 	if !teaconst.IsMain {
@@ -29,7 +30,9 @@ func SystemMemoryGB() int {
 		return 1
 	}
 
-	systemTotalMemory = int(stat.Total / (1<<30))
+	systemMemoryBytes = stat.Total
+
+	systemTotalMemory = int(stat.Total / (1 << 30))
 	if systemTotalMemory <= 0 {
 		systemTotalMemory = 1
 	}
@@ -38,3 +41,8 @@ func SystemMemoryGB() int {
 
 	return systemTotalMemory
 }
+
+// SystemMemoryBytes 系统内存总字节数
+func SystemMemoryBytes() uint64 {
+	return systemMemoryBytes
+}
diff --git a/internal/utils/system_test.go b/internal/utils/system_test.go
index df15ca1..7d81878 100644
--- a/internal/utils/system_test.go
+++ b/internal/utils/system_test.go
@@ -8,4 +8,7 @@ func TestSystemMemoryGB(t *testing.T) {
 	t.Log(SystemMemoryGB())
 	t.Log(SystemMemoryGB())
 	t.Log(SystemMemoryGB())
+	t.Log(SystemMemoryBytes())
+	t.Log(SystemMemoryBytes())
+	t.Log(SystemMemoryBytes()>>30, "GB")
 }