diff --git a/source/ledger/ledger-core/src/main/java/com/jd/blockchain/ledger/core/MerkleDataCluster.java b/source/ledger/ledger-core/src/main/java/com/jd/blockchain/ledger/core/MerkleDataCluster.java
new file mode 100644
index 00000000..d8adbcc2
--- /dev/null
+++ b/source/ledger/ledger-core/src/main/java/com/jd/blockchain/ledger/core/MerkleDataCluster.java
@@ -0,0 +1,76 @@
+package com.jd.blockchain.ledger.core;
+
+import java.util.Map;
+
+import com.jd.blockchain.crypto.HashDigest;
+import com.jd.blockchain.ledger.CryptoSetting;
+import com.jd.blockchain.ledger.MerkleProof;
+import com.jd.blockchain.ledger.MerkleSnapshot;
+import com.jd.blockchain.storage.service.ExPolicyKVStorage;
+import com.jd.blockchain.storage.service.VersioningKVStorage;
+import com.jd.blockchain.utils.Bytes;
+import com.jd.blockchain.utils.Transactional;
+import com.jd.blockchain.utils.VersioningMap;
+
+public class MerkleDataCluster implements Transactional, MerkleSnapshot {
+
+	private boolean readonly;
+
+	private MerkleDataSet rootDS;
+
+	private Map<Bytes, MerkleDataSet> partitions;
+
+	/**
+	 * Create an empty readable {@link MerkleDataCluster} instance;
+	 */
+	public MerkleDataCluster(CryptoSetting setting, Bytes keyPrefix, ExPolicyKVStorage exPolicyStorage,
+			VersioningKVStorage versioningStorage) {
+		this(null, setting, keyPrefix, exPolicyStorage, versioningStorage, false);
+	}
+
+	/**
+	 * Create an {@link MerkleDataCluster} instance;
+	 * 
+	 * @param rootHash root hash of this {@link MerkleDataCluster} instance;
+	 * @param readonly whether read only；
+	 */
+	public MerkleDataCluster(HashDigest rootHash, CryptoSetting setting, Bytes keyPrefix,
+			ExPolicyKVStorage exPolicyStorage, VersioningKVStorage versioningStorage, boolean readonly) {
+		this.rootDS = new MerkleDataSet(rootHash, setting, keyPrefix, exPolicyStorage, versioningStorage, readonly);
+	}
+
+	@Override
+	public HashDigest getRootHash() {
+		return rootDS.getRootHash();
+	}
+
+	@Override
+	public boolean isUpdated() {
+		return rootDS.isUpdated();
+	}
+
+	public VersioningMap<Bytes, byte[]> getPartition(Bytes name) {
+		return getPartition(name, false);
+	}
+
+	public VersioningMap<Bytes, byte[]> getPartition(Bytes name, boolean create) {
+		
+	}
+
+	public VersioningMap<Bytes, byte[]> createPartition(Bytes name) {
+
+	}
+
+	@Override
+	public void commit() {
+		// TODO Auto-generated method stub
+
+	}
+
+	@Override
+	public void cancel() {
+		// TODO Auto-generated method stub
+
+	}
+
+}
diff --git a/source/ledger/ledger-core/src/main/java/com/jd/blockchain/ledger/core/MerkleDataSet.java b/source/ledger/ledger-core/src/main/java/com/jd/blockchain/ledger/core/MerkleDataSet.java
index 0ea23990..896a8f37 100644
--- a/source/ledger/ledger-core/src/main/java/com/jd/blockchain/ledger/core/MerkleDataSet.java
+++ b/source/ledger/ledger-core/src/main/java/com/jd/blockchain/ledger/core/MerkleDataSet.java
@@ -31,11 +31,9 @@ public class MerkleDataSet implements Transactional, MerkleProvable, VersioningM
 	 */
 	public static final int MAX_SIZE_OF_VALUE = 4 * 1024 * 1024;
 
-	public static final String ORIG_KEY_SEPERATOR = LedgerConsts.KEY_SEPERATOR;
-
-	public static final Bytes SN_PREFIX = Bytes.fromString("SN" + ORIG_KEY_SEPERATOR);
-	public static final Bytes DATA_PREFIX = Bytes.fromString("KV" + ORIG_KEY_SEPERATOR);
-	public static final Bytes MERKLE_TREE_PREFIX = Bytes.fromString("MKL" + ORIG_KEY_SEPERATOR);
+	public static final Bytes SN_PREFIX = Bytes.fromString("SN" + LedgerConsts.KEY_SEPERATOR);
+	public static final Bytes DATA_PREFIX = Bytes.fromString("KV" + LedgerConsts.KEY_SEPERATOR);
+	public static final Bytes MERKLE_TREE_PREFIX = Bytes.fromString("MKL" + LedgerConsts.KEY_SEPERATOR);
 
 	private final Bytes snKeyPrefix;
 	private final Bytes dataKeyPrefix;