The utility model relates to the electric power system fault detection apparatus technical field, especially to a single-phase grounding line selection controlling means which is not easy to damage and comprises a housing; the inner of the housing is provided with a gatherer, an analyzer and a cell; the housing is provided with a display; the gatherer is in electric connection with the analyzer; the analyzer is in electric connection with the display. The single-phase grounding line selection controlling means also comprises a cover plate; the front of the housing is provided with installation grooves, in which button zones are arranged and are in electric connection with the display; the installation grooves are provided with a slide rail, and the cover plate is provided with a sliding chute; the cover plate is in sliding fit with the slide rail on the installation grooves through the sliding chute; and the installation grooves are provided with a neck; the top of the cover plate is provided with a cardboard which is in cooperation with the cardboard.