Laser-screen is one of the main equipments for measuring projectile-velocity, aiming at the test requirements of dot array laser-screen, the influences on the process of system debugging and measurement are studied. According to the principle of velocimetry, the influences of load resistance, illumination distance, illumination angle and angle of emission on received signals are analyzed. While the pellet passes through the device, the ideal mathematical model is established based on the actual situation of receiving component, and the relative error under different dropout voltages of timing is obtained to analyze the influence of the uniformity of the screen on the whole velocity-measuring system. The theoretical modeling and experimental analysis provide the theoretical basis and reference, for the structure design and the application of dot array laser-screen in the velocity-measuring system.