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