Abstract: This article takes 431 stainless steel forging as the research object,focusing on the hardness change of 431 stainless steel forgings after tempering at 670℃,690℃,720℃and 740℃.Meanwhile,the hardness properties of 431 stainless steel forgings after different tempering times are studied,and the microstructure mechanism analysis is carried out under different heat treatment states,to explore the appropriate tempering process to meet the organization and performance requirements of different standards(conditions of use).