The invention discloses a portable grounding device used for power transmission line maintenance. The portable grounding device comprises a main frame and a flexible connecting frame which is detachably connected with one end of the main frame. The other end of the flexible connecting frame is provided with an operation handle. The other end of the main frame is provided with a locating ring. The side surface of one end, which is provided with the locating ring, of the main frame is provided with a grounding pedal. One side of the main frame is provided with a winding rack. A locating bayonet is formed on the main frame. A grounding bar which can be matched and fixed with the locating ring and the locating bayonet is arranged in the main frame. The grounding bar comprises a bar body of which one end is conical. The beneficial effects of the portable grounding device are that installing and fixing of the grounding bar are facilitated so that the installing efficiency of the grounding bar is enhanced and the labor intensity of the fixing work of the grounding bar can be reduced; the installing and locating safety performance of the grounding bar can be enhanced; and the grounding work efficiency of circuit maintenance can be enhanced and the operation cost of the grounding work of the circuit can be reduced.