Abstract: Using model test and numerical method, the pullout process of mobile platform’s leg is simulated. In the finite element simulation, two time stepping methods are implemented to adjust the time step size. One is based on the velocity of convergence; the other is based on the truncation error estimation in temporal discretization. The results show that the displacement of the platform’s leg nonlinearly increases. To effeciently deal with this nonlinearity, the step size is reasonably arranged during the whole calculation time by the two methods. Compared with the fixed time step method, automatic time stepping method can improve the calculation efficiency and the solution accuracy.