Abstract: The deposition temperature can be hold below 570℃ by using pure ammonia durnig CVD of TiN on the surface of iron and steel parts. After deposition quenching is not necessery for the tools nmade of high speed steel. The preparation of pure ammonia used for deposition and the optinum condition for deposition at lower temperature were investigaled. The deposition rate is 2.5/μm/hr, the hardness of the layer of deposition is about 1700kg/mm², X-Rays diffraction indicates that the product of deposition on the surface is TiN.