Abstract: In the security evaluation of practical crypto system or module, the reverse analysis of unknown cryptographic algorithm is an important evaluation content. At present, the reverse analysis methods of cryptographic algorithms mainly contain mathematical analysis and physical bypass analysis, among which the latter is more popular due to its low cost and high universality. The side-channel analysis technology based on independent component analysis technology recovers the intermediate state value directly, bypassing the limitation of the “guess-and-determine” attack idea in the traditional side-channel analysis. This paper studies the safety of GIFT-like algorithm under the reverse analysis. We successfully recovered the content of the S-box by independent component analysis (ICA) technology, taking advantage of the characteristics of GIFT algorithm structure and taking the inputs of P permutation as observation conditions. The result of this paper is one of the reverse analysis results of the GIFT-like algorithm, and the method is also of reference significance to the reverse analysis of other unknown algorithms.