Plant lateral roots play an important role in soil reinforcement and slope stabilization. Investigating the mechanical effect of roots on soil, and establishing the traction effect model of lateral roots on soil may provide a basis contributing to ecological slope protection. However, traction effect of plant lateral roots on soil is intricate to be analyzed, and its model is difficult to be solved. Therefore, computer simulation appears to be a viable solution to this problem. In this paper, the traction effect model of plant lateral roots on soil was established for computer simulation on the basis of analyzing its mechanics process, and the relative computer simulation system was developed in MATLAB to provide a simulation platform for analyzing the traction effect of lateral roots. In this platform, not only the complicated model of traction effect can be solved, but also its behavior can be observed and predicted in modeling simulation by changing the input variables and model parameters. Finally, the simulation and experimental testing were implemented for lateral roots of Yunnan pine. The results show that the proposed simulation model of traction effect is of good precision, and the simulation system is valid and reliable.