The utility model relates to a process gas binary gas distribution device for a vacuum coating. The process gas binary gas distribution device comprises a cathode cover plate and is characterized by being composed of a cover plate 1, a main gas plate 2, a bottom plate 3 and baffle plates 4. The cover plate 1, the main gas plate 2 and the bottom plate 3 are sequentially assembled and arranged on the lower surface of the cathode cover plate, and the baffle plates 4 are arranged on two sides of the cathode cover plate. The lower surface of the main gas plate 2 is provided with a main gas outlet groove and an auxiliary gas outlet groove in an alternating mode. The upper surface of the main gas plate 2 is provided with a main gas binary structure gas distribution groove 5, auxiliary gas binary structure gas distribution grooves 6, 7, 8 are arranged on the upper surface of the bottom plate 3, the process gas binary gas distribution device can be divided into three to seven independent sections along the length direction of a cathode target, and the auxiliary process gas supply amounts of different positions along the length direction of the cathode target are respectively and independently controlled. Even distribution of process gas along the length direction of the cathode target is achieved, and the use radio of target materials and film coating quality are improved. Meanwhile, the process gas binary gas distribution device for vacuum coating has the advantages of being simple in structure and convenient to mount and maintain.