Cat-eye effect widely existing in electro-optical imaging system is researched. According to the retro-reflection property of a cat-eye target, a mathematical model under different echo wave intensity is established. Based on the model and TracePro software, the cat-eye effect of a typical target with different laser emission distance, lens focal shift and incident angel is simulated and analyzed. Results show that theoretical calculation accord with the simulation results, so it can be used to guide laser active detection system design in the future.