To explain the jamming mechanism of CCD that is irradiated by laser,the theoretical simulation model is established based on finite element method. The simulation model is used to calculate the saturation jamming area of Si-CCD irradiated by 632 nm lasers with different optical power. The "bucket" model is established,and the finite element simulation mode is established by using the electron and hole diffusion theory of the semiconductor PN junction,and then simulations of the effect that the laser interferes CCD are carried out for the two models. The saturation interference areas are obtained under different optical powers and compared with experimental results. The results show that "bucket" model can′t explain the experimental phenomenon better,and the saturation interference area of the finite element simulation model is closer to the experimental results. Therefore,the finite element simulation model can be used to predict the actual interference effect.