Abstract: In order to modify the biocompatibility of NiTi shape memory alloy,ion nitriding was used to perform nitriding on the surface of NiTi SMA alloy.The microstructure and characteristics of the nitrided surface were investigated by the methods.The results show that by ion-nitriding a tense TiN layer is obtained on the outer surface and a Ti2Ni transition layer is present between the outer surface and NiTi substrate,which has greatly enhanced the corrosion resistance of NiTi shape memory alloy and excellent cohesion between the nitride layers and substrate is achieved.