Abstract：By analyzing the linear property of Keccak f permutation functions of SHA-3 algorithm and the roundreduced preimage attack of Keccak hash function, an optimization of preimage resistance on SHA-3 algorithm is proposed. Firstly, we combine the differential property of Keccak algorithm and even parity of θ permutation function, and analyze the preimage resistance of SHA3 algorithm based on CPkernel. Secondly, according to the current preimage attack methods on SHA-3 algorithm, the output of θ permutation function XOR random numbers are used to change Hamming weight and to improve the properties of CPkernel. It prevents an attacker from using meetinthemiddle method to find the preimage. Finally, the scheme has been implemented with VHDL hardware language. And, the results show that the encryption process has a good performance and high security.