The utility model discloses a grounding device of a distribution box. The grounding device comprises an iron bolt (2) and a copper binding post (4), wherein the bolt (2) is welded at the inner side of a distribution-box door (3), the binding post (4) is connected with a lead of a grounding copper bar in the distribution box, one end of the binding post (4) is fixedly connected with the lead of the copper bar, and the other end of the binding post (4) is sleeved on the bolt (2). According to the above structure, grounding resistance is not increased while the structure is simplified, thereby saving material of copper wires and further reducing the cost.