Abstract: In order to simulate the growth of plants sharing light resource more realistically, a method of modeling the growth of plants sharing the sunlight in the same area was presented in this paper. Considering the aspects of shape and darkness degree, the model was developed based on FON model. Furthermore, some geographical and biologic factors were used in this method, such as the latitude value of the location of plants, shading rate, and the light sensitivity attribute of plants in order to more truly simulate the growth of plants sharing the sunlight. In order to verify the availability of this method, the biomass of the mixed forest for northeast China manchurian ash and larch was analyzed and compared based on the simulation result. In addition, a simulation system of plants sharing light resource was implemented which could simulate and visualize the growth phenomenon of the plants with different competition status. The simulation results showed that the method of modeling the growth of plants sharing the sunlight in the same area could simulate the plant growth accurately and be applied to the actual simulation of plant growth.