Aiming at the problems of low energy utilization and environmental sensitivity of passive light source adopted in high-speed projectile flight parameter measurement system, a combined active laser shadow photography system was studied. Based on the theoretical analysis of the system, the space position model and two velocity measurement models of high-speed projectile were established. The experimental platform of laser shadow photography system was built and the rationality of the system design was tested. The test results show that the both models can measure the flight speed of projectile, and the comparison error between the two methods is small.The mean square deviation of the projectile space position in X-axis is 0.795 mm and that in Z-axis is 0.496 mm. Compared with the results of paper target, the deviation degree is within 1 mm, and the system can measure the flight parameters of the projectile.