i don't know if there is an error in the scriptsig generation method of input in p2psh I don't know if there is an error in the scriptsig generation method of input in P2PSH.

My address is a single signing address with one Private key，
I created a transaction that will generate hex string via Bitcoinj.

script = ScriptBuilder.createOutputScript(key.getAddress(params));
Sha256Hash hashForSign = transaction.hashForSignature(i, script, SigHash.ALL, false);
ECDSASignature signature = eckey.sign(hashForSign);
TransactionSignature tranSign = new TransactionSignature(signature, SigHash.ALL, false);
scriptSig = ScriptBuilder.createInputScript(tranSign, eckey);


But it is not the same as the hex string generated by the client RPC, but I don't know where it is wrong.

I will be very grateful if you can help me.
ECDSA signatures are not deterministic unless you are using a deterministic signature scheme. Meaning that signing the same data with the same key produce different (valid) signatures. 

I don't know if Bitcoinj uses such a scheme so If only the signature bytes in the transaction are different it is probably  fine.