Grass is one of the nature elements that is difficult to simulate in real-time due to its large number and wide covering range. In view of the deficiencies of existing methods, a method for simulation of treading on grass was proposed. Constructed largcscale static grassland based on hybrid representation. Computed the deformation of grass close to the viewer by using GPU-based real time collision detection algorithm and force vector diffusion mechanism. Simulated the deformation of tussock by adjust the slope of billboard. In order to avoid popping between different levels, a transition scheme was implemented. Experiments show that this method not only can realistically simulate the effect of treading on grass,but also can overcome the deficiencies of the traditional methods.