Application of chemical deposition technology,a layer of nanometer TiN-Ni alloy is coated in the planet gear shaft of automotive transmission,the tests show that the nano-TiN particle increase the hardness and the wear-resisting performance and the chemical resistance of the plating of TiN-Ni alloy,also increase the friction coefficient for it.The nano-TiN particle is diffused in the unit cell of the layer of nanometer TiN-Ni alloy,they form the plating of metal alloy and ceramic,the plating is densification and hardness,there are a lot of the hardness nano-TiN,the mechanical property of TiN-Ni alloy coating is improved.