Abstract: In this paper , the present situation of secondary system grounding in substation is comprehensively analyzed, Some improvement measures, such as perfecting the setting of the secondary grounding grid, improving the anti-interference ability of the secondary device, canceling the insulated copper bar in the cabinet, making clear the grounding mode of cable shielding layer, increasing the protection of the weak electrical signal cable, standardizing the connection mode of the serial communication, have solved the problem of grounding frequently occurring in engineering.