The value selection of m has a greater influence on the internal force of pile. So, how to determine the value of m is very important for the “m” method. In this paper, a geotechnical finite element software PLAXIS is used for the nonlinear finite element analysis of elastic long pile under the horizontal force action. By using the calculated maximum bending moment and the maximum displacement at the ground, and combined with the related formula for “m” method given in 《Code for Pile Foundation of Harbour Engineering》, a more accurate value of m can be obtained conveniently. Because this method is simple and practical, it can provide a useful reference for the project designer to determine a reasonable value of m.