Abstract: Particle size is an important factor affecting the performance of hydrogen storage alloy powders, and the abnormal fluctuation of particle size will lead to the decrease of the yield of Ni-MH battery negative electrode. The factors that may affect the particle size in the process of hydrogen storage alloy powder production were verified and analyzed, especially for the dry process of alloy powders, the key parameters of powder production equipment, analysis and testing equipment and sieve mesh were verified. The results show that the abnormal particle size distribution of the products in the pulverizing process has no obvious correlation with the pulverizing equipment and testing equipment, and the main cause of particle size problem is the deviation of wire diameter of screen used in pulverizing, and effective control measures are formulated accordingly.