In order to reduce the calculation amount of immune algorithm application, the principle of artificial immune algorithm is analyzed in this paper, an artificial immune algorithm based on auxiliary medicine is proposed, and then, its application in function optimization is studied. The process of traditional immune algorithm is changed, with a medical treatment in it to promote the human immune system to eliminate foreign antigens. The novel immune algorithm divides the original objective function. When a local minimum is found in the global search process, the search area is updated. Finally, the algorithm is used to search for the minimum value of multimodal functions, and the simulation experiments verify the feasibility and superiority of the proposed algorithm.