Abstract: Annealed La_0.6Y_0.4Ni_3.75Al_0.15Mn_0.2 superlattice hydrogen storage alloys were prepared using a vacuum arc-melting furnace and a vacuum tube-type annealing furnace. The alloys were subsequently ball-milled for 1,3 and 6 h under inert atmosphere protection. The effects of ball-milling time on the surface structural characteristics and electrochemical properties of the hydrogen storage alloys were investigated. XRD results indicate that the untreated alloy consists of CaCu₅,Pr₅Co₁₉,and Ce₅Co₁₉ type multiphase structures. After ball-milling,the phase structure of the alloy remains unchanged.however,the diffraction peak intensities are significantly reduced and pronounced peak broadening is observed,suggesting the formation of amorphous and nanocrystalline structures. SEM and EDS analyses show that ball-milling markedly reduces the particle size,eliminates sharp edges,and results in nearly spherical particle morphology. Moreover,the elemental distribution remains uniform after ball milling,indicating that the process does not alter the elemental distribution. Particle size analysis reveals that the powder particle size decreases significantly after ball-milling,exhibiting a decrease-increase trend with prolonged milling time. As the ball-milling duration increases,the activation performance of the alloy electrodes is notably improved and the maximum discharge capacity as well as other electrochemical properties first increase and then decrease. When the ball-milling time is 3 h,the maximum discharge capacity increases from 318.5 mA·h/g(without ball-milling) to 339.4 mA·h/g, and the high-rate dischargeability HRD₁₂₀₀ increases from 77.6% to 80.5%.Ball-milling has a significant positive effect on enhancing the hydrogen storage performance of the alloy,and an appropriate ball-milling treatment can effectively optimize its microstructure and electrochemical properties.