GS-LPSA1100 laser particle size on-line monitoring system is an equipment for on-line monitoring of powder particle size distribution after material grinding. Based on the principle of laser diffraction and Chahine inversion algorithm, the system measures the powder particle size distribution online. The mill operator can reasonably adjust the amount of abrasive and mill current according to the measured particle size information to achieve the optimal control of material particle gradation and realize high quality, high yield and low consumption of material grinding.