In order to improve the defects of the basic fruit fly algorithm, an improved drosophila algorithm was used for optimization. The basic idea is to improve the searching ability and accuracy of the algorithm by using the self-non-self antigen recognition mechanism of immune algorithm and the knowledge processing mechanism of learning-memory-forgetting in immune system improves the searching ability and accuracy of the algorithm. The improved algorithm introduces the immune response at the later stage of fruit fly algorithm implementation, and enhances the population diversity by producing different antibodies to jump out of the local optimal. The results of numerical simulation and practical cases show that the improved algorithm performs better, which provides an effective and feasible method and idea for algorithm optimization.