The invention discloses a magnetron sputtering cathode target used in an ultra-high vacuum system. Its upper and lower flanges (15, 16) are built with intercommunicating cooling water tanks (13, 9), and the inlet and outlet pipes (1, 2) cut off the cooling water tank (9) and are welded to it, and the upper flange (15) The upper end is screwed to the target mounting cover (12), the magnet holder (10) and the magnet (11) are placed in the cavity, and the inner and outer knife edges (7, 8), the metal sealing rings (17, 18) at the place are fixed by screws (14), and the small flange (21) is welded outside the outlet pipe (2), and it is connected with the shielding cover (19) and the base flange (22) ) is interposed with insulating sheets (4, 6), and two ○-shaped rubber rings (23, 24) are interposed with the base flange (22) through which the exhaust pipe (3) penetrates, and are insulated through their outer sleeves. The screw (20) of sleeve (5) is fixed. Its vacuum degree is as high as 6×10-8Pa, which can realize the preparation of high-quality and high-purity metal or non-metal thin films.