Aiming at the problem that searches step δ′ parameter is invariable in the process of SAGACIA optimization algorithm, the improved adaptive step was presented, which made the step parameter δ′ change adaptively in the process of optimization. And the modified adaptive SAGACIA optimization algorithm was used in optimizing multimodal function, which efficiently solved the partial search performance and the global convergence. The results of the applications showed that the modified SAGACIA optimization algorithm was practical and efficient.