Simulated shells were designed as the experimental projectiles, the flight velocity of fragments in multi-projectile explosion and single projectile explosion were studied by using on switch target and multi-channel time interval measuring apparatus, the flight velocity of fragments was also found and the flight velocity of fragments was comparatively analyzed by Gurney equation. The research results show that the flight velocity of fragments in multi-projectile explosion and single projectile explosion are similar, the two results are smaller than the calculation result of Gurney equation.