Magnetic annealing were carried out for Nd0.75Mg0.25(Ni0.8Co0.2)3.8 hydrogen storage alloys at different temperatures. The electrochemical properties, magnetic properties, phase composition and lattice parameters of alloys were systematically investigated. The results show that magnetic annealing has little influence on phase composition of alloys, which includes Ce2Ni7 type (Nd,Mg)2(Ni,Co)7 phase and CaCu5 type NdNi5 phase. Magnetic annealing results in the orientation of easy magnetization axis along c axis. As the annealing temperature increases, the lattice parameter c is increased, which coincides with the extension of tetrahedral interstitials along c axis. Additionally, the obstacle of transportation for hydrogen proton decreases and the rate properties are improved with the annealing temperature increasing