Abstract: In this paper, ACO algorithm is reviewed by and large. Firstly, the corresponding principle of biont and the implementing framework for ACO algorithm are introduced simply. Then, the actual research status of ACO algorithm is discussed in detail. The applications of ACO algorithm in all kinds of optimization problems are analyzed thoroughly. Some deficiencies of ACO algorithm in practical applications are also presented. Combining solution methods for those deficiencies, several correctional strategies for ACO algorithm are described. Finally, research directions of ACO algorithm in the future are proposed.