In order to improve the terminal impact angle of conventional proportional guidance law, a revised proportional guidance law based on the line of sight angle and the velocity vector prepositive angle was proposed in this article to meet the terminal impact angle requirement. Finally, some simulations were applied to analyze the character of the trajectory and the influence of missile speed and the measurement error of parameters. The results show that the proposed guidance law can enhance the terminal impact angle greatly with equivalent attack precision of conventional proportional guidance law and has strong robustness.