Abstract: To investigate the change of microstructure and properties, laser transformation hardening was carried out on 1Cr18Ni9Ti stainless steel, and the microstructure and properties of laser transformation hardened layers were investigated by means of scanning electron microscope, X-ray diffractometer, microhardnessmeter, abrasive wear testing machine, potentiostat etc. The hardness, wear resistance, corrosion resistance data of laser transformation hardening layer were obtained by theoretical analysis and experimental verification. The result indicated that the laser transformation hardening layer was mainly consisted of austenite, martensite, Fe-(Cr, Ni), Fe etc. With the increase of the laser power, the average microhardness of laser hardening layers increased first and then decreased. The average microhardness reached the highest (223.5HK) when laser power was 750W. Wear resistance reached the best (whose wear rate is 56% of the substrate) when the power was 550W. Corrosion resistance was improved after laser transformation hardening, passivation current density of the smallest dimension was 33% of the substrate, the maximum length of the passive zone of stability was seven times of the substrate. The results are helpful to study the change of microstructure and properties of 1Cr18Ni9Ti stainless steel.