Abstract: The traditional L grammar method is hard to be employed for the user to establish tree models,and the efficiency of the simulation system is too poor to meet users' demand for real-time walking-though.In order to solve the problems,this paper presents a novel approach to simulate tree growth in a run-time forest scene.By this approach,the fractal is applied to model the tree structures. In addition,the rendering efficiency of the large scale forest scene is enhanced by adding a view-dependent multi-resolution billboard algorithm.Some experiment results are presented in the paper to validate this approach.The experimental results show that the approach proposed in this paper can be applied to simulate the tree growth in a run-time forest scene accurately,and meet the demand of real- time walking-through in virtual forest scene.