Abstract: A powerful method for numerical simulation of ultimate bearing capacity of complex foundation is proposed in this paper. The method is applicable to any type of complex foundations due to the application of the slice method in slope stability analysis and the general slip surface. The calculation of ultimate bearing capacity for foundation is reduced to an optimized numerical model after some mathematical operations. A coupling algorithm combining simulated annealing algorithm and random search method is introduced. The numerical results of the present method for several practical examples agree well with field experiments. It is believed that the present method is very effective in evaluating ultimate bearing capacity of complex foundations.