Abstract: Plastic deformation with different levels was carried out by means of uniaxial tension tests at room temperature(25 ℃) for 1Cr18Ni9Ti stainless steel.The relationship between plastic deformation and content of α′-martensite phase was obtained by means of ferrmagnetometor.The corrosion behaviour of 1Cr18Ni9Ti stainless steel with different levels of plastic deformation was studied by means of chemical immersion method and electrochemical method in acetic acid solution containing Br-.The cold working deformation induced martensitic phase transformation,which resulted in increase in corrosion rate and decrease in pitting potential and pitting corrosion sensibility of deformed 1Cr18Ni9Ti stainless steel in acetic acid containing Br- ion.However,the corrosion resistance of 1Cr18Ni9Ti stainless steel with 18%-27% plastic deformation was improved.