Abstract: The effects of composition and structure on corrosion behavior ofNd-Fe-B alloy have been studied.The potentials of all main phase of Nd-Fe-B alloy in pure water and NaCl solution were measured.The order of potential is E_(Nd-rieh)<E_{(Nd2Fe14B major phase)}<E_(B-rich).The corrosion characteristic of Nd-Fe-B permanent alloy is that the Nd-rich grain boundary phase in the alloy is easier to be corroded than the Nd₂Fe₁₄B grain phase.The experiment results of eviromented corrosion tests showed that the corrosion resistance of the Nd-Fe-B alloy in solution is improved by the addition of Dysprosium,but reduced by the addition of Aluminium to the alloy.