Abstract: In this paper, the finite element analysis software LS-DYNA was used to establish a three-dimensional model of TC4 particle impact on TC4 substrate. The Gruneisen equation of state and Johnson-Cook material model were adopted to simulate the situation of particles with different radii impacting the substrate at the same speed and the same particle impacting the substrate at different speeds. The influence of different radius and velocity of particles impacting substrate is analyzed. The TC4 coating was deposited on the TC4 substrate by cold spraying technology, and the variation trend of hardness in different parts of the coating was studied. The results show that when TC4 particles impact TC4 substrate at different velocities, the sputtering phenomenon is more significant with higher velocities. When TC4 particles with different radius impact TC4 substrate with the same speed, the larger the particle radius is, the more significant the metal sputtering phenomenon is. Under different spraying pressures, the hardness of the coating changes in the same trend, from the bottom to the top, the hardness gradually decreases. The simulation results describe the collision process in a short period of time which is difficult to be observed by experiment, and the hardness trend of the coating is obtained by experiment.