By studying the signals and noise generated by the photoelectric detector and operational amplifier when the target passed through， the theoretical relationship between the signal-to-noise ratio and the laser output power was derived， as well as the retroreflection efficiency of the original reflection screen. Multiple sets of experiments were conducted to verify the influence of laser power and reflection efficiency on signal-to-noise ratio. The results indicated that， by appropriately increasing laser power and using a reflective screen with high reverse reflection efficiency， the signal-to-noise ratio of high-speed small target passing signals could be effectively improved in the designed laser screen system.