By combination of DC reactive magnetron sputter i ng with multiple arcplating, the alternating C 3 N 4 /TiN compo und film is deposited onto HSS. The core level binding energy and the contents o f carbon and nitrogen are characterized by X|ray photoelectron spectrum. X|ray diffraction(XRD) shows that compound thin film contains hard crystalline phases of α |C 3 N 4 and β |C 3 N 4 . The Knoop microhardne ss in the load range of 50.5|54.1 GPa is measured. According to acoustic emissi on scratch test, the critical load values for the coatings on HSS substrates are in the range of 40|80 N. The metal coated with C 3 N 4 /TiN compound f ilms has a great improvement in the resistance against corrosion. Many tests sho w that such a coating has a very high wearability. Compared with the uncoated an d TiN coated tools, the C 3 N 4 /TiN coated tools have a much longer cut ting life. By combination of DC reactive magnetron sputter with multiple arcplating, the alternating C 3 N 4 / TiN compo und film is deposited onto HSS. The core level binding energy and the contents of carbon and nitrogen are characterized by X ray photoelectron spectrum. X | ray diffraction (XRD) shows that the compound thin film contains hard crystalline phases of α C 3 N 4 and β C 3 N 4. The Knoop microhardnes ss in the load range of 50.5 | 54.1 GPa is measured. According to acoustic emissi on scratch test, the critical load values ​​for the coatings on HSS substrates are in the range of 40 80 N. The metal coated with C 3 N 4 / TiN compound f ilms Has a great improvement in the resistance against corrosion. Many tests sho w that such a coating has a very high wearability. Compared with the uncoated an d TiN coated tools, the C 3 N 4 / TiN coated tools have a very longer cut ting life .