Abstract: Two stage light gas gun is one of the important devices to simulate hypervelocity impact effect of space debris. Firstly recent development about two-stage light gas gun is reviewed. The principle of two-stage light gas gun, its driver gas and test things are expounded. And then certain parameters affecting performance of two-stage light gas gun are discussed, including initial pressure, piston velocity, burst pressure, piston mass, projectile mass, etc. As two important performance indexes of two-stage light gas gun, , the measurement technologies of projectile velocity and dynamic impact angle are presented finally.