Abstract: With the continuous improvement of the loading rate of projectiles in gas guns and their testing accuracy, the requirements for the uniformity and parallelism of the light energy distribution of the light curtain of the laser test system are getting higher and higher. A diffractive optical element（DOE） is used to shape the laser beam into a linear uniform beam, and a Fresnel lens is utilized to form a uniform parallel light curtain, which passes through a 1/3 beam splitter, a half-transparent half-reflector and a total-reflector mirror to realize a highly parallel integrated single-light-source three-light curtain. Using the improved GS algorithm to design the DOE element to obtain a linear distribution of the beam, the uniformity of the experimental test is 83. 7%; the parallelism of the three-light curtain is tested, and the maximum deviation is 0. 279 mrad. This single-lightsource three-light curtain system can meet the needs of ultra-high-speed gas shell speed measurement on the sensitivity of the light curtains and the demand for speed accuracy.