Abstract: Aiming at the influence of the noise and other factors in the process of classical correlation power analysis, based on the linear correlation between Hamming weight and power traces, a correlation power analysis method for AES cryptographic chip is proposed. According to the uneven distribution of the median Hamming weight of the S-box output of the cryptographic algorithm, a set of plaintexts with strong correlation with the power traces is obtained by filtering the correct keys and the wrong keys by using the discrimination ratio. In the stage of key recovery, the leakage points of the first two S-boxes are found by observing this set of plaintext inputs, and the leakage intervals of the remaining 14 S-boxes are found one by one by using the separate guessing method, so that the key information of the remaining bytes can be captured without traversing all power traces. The experimental analysis of AT89S52 chip shows that the proposed method can correctly recover the one-byte key of AES with 90% success rate by using only 9 plaintexts and corresponding power traces, and the computational complexity is only 4.1% of the classical correlation power analysis, which significantly improves the efficiency of the correlation power analysis.