The utility model discloses a double-gap expansion joint usable for a metro power supply contact rail system. The double-gap expansion joint consists of a divider, support plates, an auxiliary divider, an auxiliary support plate, long guide plates, short guide plates, fishplates, movable rails and a fixed rail. According to the double-gap expansion joint, extension and retraction gaps and angles of the gaps can meet the sliding requirements of electrical shoes, and the overall extension and retraction gap of the expansion joint is enlarged to 200mm to meet the requirements of operation at extreme environmental temperature.