Abstract: A safety cover comprises an inner plug and an outer cover. The coupling portions of the inner plug and outer cover are alternatively arranged with stopper and ribs. The inner surfaces of the limiting stoppers coupling to the ribs are inclined. When the ribs of the inner plug are separated from the limiting stoppers of the outer cover, the inner plug dose not rotate with the rotation of the outer cover. When the user presses the outer cover slightly, so that the buckle ring of the outer cover is embedded into the annular flange of the inner plug, the stopper ribs of the outer cover exactly slide along the limiting stoppers of the inclined surface of the inner plug to buckle the limiting stoppers. Thereby, the stopper ribs of the outer cover resist against the limiting stoppers of the inner plug to rotate therewith.