In-flight behavior of particle in plasma jet is one of important factors, which affect the quality of workpiece formed by
plasma spraying. Through the momentum and energy transfer equation established by the theory of particle-plasma interaction in plasma jet, the laws of velocity and temperature field have been simulately calculated by the finite difference method to analyze their effect on the quality of
plasma spray forming (PSF). The results show that: (1) The acceleration of particle increases with the decreasing of diameter and density, but its velocity arriving the
prototype is different. (2) If the diameter of particle is bigger, and its heat conductibility is poorer, its extremum temperature is lower, and the extremum point is shifted to the prototype gradually. (3) By matching the mechanical behaviors with heating characteristics, the quality of PSF is further improved. The computational results provide the basic theory to realize the quality control and parametersoptimization in PSF.