Software homology detection is very meaningful for software copyright protection and malicious code variants detection. In this paper, we propose a genetic algorithm to justify the binary code similarity. First of all, the binary executable les are converted into control flow graph, and then use genetic algorithm to compute the similarity among control flow graphs, which is regarded as the evaluation metric for software homology detection. The experimental results show that the method is not only effective, but also the average time efficiency is 0.3 times that of the classical algorithm of graph edit distance.