Abstract: In this study, the macro morphology of the powder flow was obtained using a high speed camera, and image gray processing was implemented to study the effect of process parameters on powder flow feed behavior. The feasibility of research method was estimated. Results showed that the powder density can be obtained accurately from the gray level information. Distribution of the powder density in cross section at the focus position typically obey Gaussian distribution. The effect of powder feed rates on the position of powder focus can be neglect. With the increase of carrier gas flow rate, the position of powder focus and diameter of the focus plan decrease. The critical value of the coaxial protect gas flow rate was 8 L/min, the trajectory of powders maybe changed for vortex phenomenon when greater than this value.