Particles impacting at high velocity is a very important research direct in impact dynamics field. A SPH model with 10 particles of three layers was built using SPH mesh free method, and copper particles impacting at high velocity under shock load was simulated in two dimensions. The results of particles deformation under four different shock velocity were obtained. Comparing and analyzing the results, it was found that, for copper particles with diameter was 1mm, only when shock velocity reached 300 m/s copper particles would shape jet and penetration, and the jet velocity was about 1500 m/s. The research results indicate that jet formation is the necessary condition of firm combine when powder particle impacting at high velocity and jet formation is related to the shock velocity of dynamic load.