Abstract: Coaxial Laser powder feeding additive manufacturing involves complex interaction between laser beam and powder particles, which is also the key to determine the effective utilization of laser energy. Therefore, based on the real-time value and the average value of the bright area of powder particles in time series, the interaction process of light and powder and its influence on the residual laser energy for melting matrix are analyzed by using the back image enhancement transient effect capture technology and image processing technology. The results show that the powder feeding rate and the distance between the powder and the powder are the key factors affecting the effective melting matrix energy; the increase of the carrier gas flow rate increases the flying speed of the powder particles, but has little effect on the loss of laser energy after the interaction of the powder and the powder; when the particle size of the powder is small, the more intense the interaction process of the powder and the effective melting matrix energy decreases. In general, the size of the bright area is positively related to the loss of laser energy when the particle velocity is constant.