Abstract: Particle size and Particle size distrubition is the most important character of powders. We test rare earth permanent material NdFeN, particle size is analysed by laser light scattering method (dry method and wet method) and SEM, then the three test results are compared. The test results show, when the particle size is analyzed the abundant scattering of the sample is a foundation measured accurately. Combine the intuition of microscope and fast, accurately, conveniently of laser size instrument, for guaranteeing the reliability of the particle size analysis result is very useful.