Abstract: The research on the security of McEliece (M) public key cryptosystem was presented. The Hamming weight of error vector is less than the code length, and M public key cryptosystem based on Goppa code possesses low weight public code words. Considering the above analysis, an attack algorithm based on enumeration error vector was proposed. The effect on probability of correct decryption by the numbers of error flipping bits and algorithm iteration was focused on. And the security of (1 024,524,101) Goppa-based M public key cryptosystem was analyzed. Performance analysis of the proposed algorithm from probability of correct decryption and work factor was simulated, and the experimental results show that the proposed algorithm has a good performance when the code weight is low.