To solve some existing problems in multi-modal function optimization,an improved Clonal Selection Algorithm(CSA) based on the backtracking mechanism,Backtracking Clonal Selection Algorithm(BCSA),was proposed in this paper.The global search capability could be enhanced by using the improved backtracking mechanism and the restraining operation of memory antibodies,which maintained the diversity of antibodies.In addition,in order to improve the convergence speed,the improved dynamic mutation,selection and crossover operation were adopted.The results tested on typical multi-modal functions show that BCSA has a powerful performance in global search.