After 32CrMoV is selected to manufacture nitrided gears coated with TiN by multi-arc ion plating,all of these uncoated gears and coated gears run in the gearbox under the same initial condi- tions so as to compare their difference concerning properties and microstructure.Experiment results indicate that tooth surface of the coated-TiN gears does not suffer surface abnormalities in meshed zone.Instead,the gears with nitrided case exhibit an abrasion mark on the meshed zone of tooth sur- face,which results in more weight loss of nitrided gears.The morphology of the surface suggests TiN film with more than 2000HV is so dense and smooth that coated-TiN gears have higher wear resis- tance compared with the uncoated gears.The microstructure of coated-TiN gears is finer,hardness is higher and its distribution of coated=TiN gears is more reliable than uncoated ones,which makes nitride layer combined with TiN film tightly.Consequently,the wear-resistance of gears has been dramatically promoted. After 32CrMoV is selected to manufacture nitrided gears coated with TiN by multi-arc ion plating, all of these uncoated gears and coated gears run in the gearbox under the same initial condiments so as to compare their differences concerning properties and microstructure.Experiment results indicate that tooth surface of the coated-TiN gears does not suffer surface abnormalities in meshed zone. Instead, the gears with nitrided case exhibit an abrasion mark on the meshed zone of tooth sur face, which results in more weight loss of nitrided gears. The morphology of the surface suggests TiN film with more than 2000HV is so dense and smooth that coated-TiN gears have higher wear resistivity compared with the uncoated gears. Microstructure of coated-TiN gears is finer, hardness is higher and its distribution of coated = TiN gears is more reliable than uncoated ones, which makes nitride layer combined with TiN film tightly.Consequently, the wear-resistance of gears has been as promoted.