Abstract: The effects of complexes on the content and contribution of P element,morphology and corrosion resistance of electroless Ni-P alloy coating have been investigated.The results,obtained by immersion test,SEM observation after corrosion test and EDS composition analysis,showed that corrosion resistance of the coating depends on the P content in the coating,and associated with the surface morphology of coating and variation of P content.Further analysis indicated that all of these discussed above are related to the kind of complex selected.