This paper deals with salt bath nitro-carburising processes of high chroumium amounts heat resistant steel and stainless steel and develops a proper nitro-corburising salt bath and heat treatment process.The film of oxide for high chroumium amounts steel can be removed directly and the case hardness, wear resistance and synthetic property of parts can be improved considerably as well,There is no environment pollution in this process.The equipment and operation of the process are simple; its cost is moderate.It is appropriate for the batch production of small-or medium-sized parts with complex shape of these steel.