The invention relates to a sulfur hexafluoride gas partial discharging detection method under X ray irradiation and an apparatus thereof. The apparatus comprises a test transformer (1), a GIS test section (2), a high voltage lead wire (3), a sleeving (4), an insulating defect position (5), a high frequency X ray machine (6), an X ray emission window (7), a quadrangle support (8), a high frequency X ray machine control box (9), a verification device (10), a detection impedor (11), a cable (12), a collection device (13), a battery cable (14), a battery set (15), an optical fiber (16), an optical fiber controller (17), a USB wire (18), a portable pulse current industrial computer (19) and a coupling capacitor (20). According to the invention, advantages of high efficiency, losslessness and visualization and the like are realized.