The secondary electron emission is widely used in production practice, but it is difficult to measure accurately because the measuring result is severely affected by the experimental environment and equipment. A model of secondary electron emission is proposed in this paper. The model has three sections: the generation of secondary electrons, the motions of secondary electrons inside the solid and the escape of secondary electrons from the solid surface. Based on Monte-Carlo method, the relationship between the secondary electron emission coefficient and the range of energy with the energy and angle of the incident electrons is also analyzed. Simulation results show that the model proposed in this paper is corresponding to the actual condition very well. The relation between the secondary electron emission coefficient and the range of energy with the energy and angle of the incident electron is obtained.