Abstract: A three-dimensional finite element model was developed to analyze the strain-stress and the deformation performances of soil nailing,and the reasonable distribution of soil-nail stress was presented.Based on these,using complex algorithms,optimal design of soil nailed structure was studied considering horizontal soil displacement.The mathematical model for optimal design of structure was established and the calculation program was compiled.By analyzing an example and comparing with the optimal results based on the ultimate balance analysis,the reasonable results of optimal design of soil nailed structure were obtained.