Abstract: In order to solve the technical problem of the incorrect signal of optical screen due to disturbance of mosquitoes, impact wave or noise from photoelectric device, a digital signal processing algorithm was put forward. The algorithm used the data acquisition (DAQ) instrument to collect signals of the projectile passing through the screen, and then used 3 criterion to remove singular points. The triggering moment of the half peak could be selected correctively by means of the 4-power Gaussian curve fitting for the sampling data to achieve high-precision measurement with the lower sampling rate after the time frame of the projectile signal was determined by threshold comparison. The testing results of the computer simulation and the ball firing show that the algorithm is correct with high efficiency. The testing result of the ball firing of the XGK-2002 optical screen shows that the algorithm is eligible to measure the moment when various projectiles crossing through the screen and improves the application field and stability of the light screen target, the measurement relative error of the algorithm is less than 0.1％. The algorithm is also applies for the extraction and calculation of dynamic characteristics of this kind of signals such as sky screen target.