Abstract: In view of the time-consuming problem of the traditional testing methods of transformer dielectric loss factor and capacitance test, the QC team reformed the ground wire used in substation and developed a universal insulating fastening bracket for test cable to enhance the fixing performance of the bottom support of the test line. The result eliminates the disadvantage of too long overlapping part of test line, effectively shortens the testing time of transformer dielectric loss factor and capacitance, and improves the working efficiency.