Maximum entropy principle is imported into the basic complex method in order to improve the ratio of successful run. A new search idea is presented as follows: firstly the search optimum design point is defined as the design point whose entropy is the biggest among all the design points of the complex and a new better design point is found on the line through the search optimum design point and the integrated centroid of the remaining design points. A new complex is generated after the search optimum design point is replaced with the new better design point. The method iterates until the information of the complex is utilized thoroughly thereby proposing a new complex method. The basic complex method and the complex method based on maximum entropy principle are used to locate the critical failure surface with the minimum factor of safety of two non-homogeneous soil slopes and the comparisons of the results suggest that the ability of the complex method based on maximum entropy principle to find global optimum is stronger than that of the basic complex method.