As a common passive jamming mode, smoke screen has a direct impact on combat effectiveness. The jamming principle of smoke screen is introduced, the relationship between the shading effect and the launching speed, launching angle and fuse time of the smoke screen grenade are described, and the influence of the three parameters on the shading effect is analyzed. Simulation results show that the smoke screen shading effect is the best when the firing speed is the maximum, the launching angle and the fuse time are the appropriate values during the adjustable range of parameters. And the conclusion is helpful for practical application.