The invention discloses a device for detecting a gas valve matching surface of a gas meter. According to the device, a two-dimensional air-flotation locating platform is mounted on a working platform, a workpiece clamping device is fixedly arranged on the two-dimensional air-flotation locating platform, a valve cover and a valve body of the gas meter are fixedly arranged on the two-dimensional air-flotation locating platform by using the workpiece clamping device, a flat plate is vertically mounted on the working platform through two reinforcing plates, a ball screw is mounted between a fixing seat and a supporting seat, a servo motor is fixedly arranged on a motor mounting rack and is connected with the ball screw through a shaft coupling, a slide plate is mounted on a slide block on a linear guide track so as to realize the movement of the slide plate in the vertical direction, a bracket is fixedly arranged on the slide plate, and a laser triangle displacement sensor is mounted on the bracket. The device disclosed by the invention is high in detection accuracy, good in stability and convenient in operation and is suitable for quickly detecting whether the gas valve matching surface of the gas meter is qualified or not in a workshop by workers.