The utility model relates to an open-air natural gas station yard leakage detection device comprising an instrument support pier, the bottom end of which is fixed under the ground surface, and the topend of which is fixedly provided with an installation backboard; the ultrasonic leakage detector is fixed to the mounting back plate and right faces the ground surface, and a gap is reserved betweenthe ultrasonic leakage detector and the instrument support pier. The beneficial effects of the utility model are that the probability of leakage detection is improved, and the false alarm rate is reduced. Waterproof and anti-corrosion measures are adopted, so that the device is suitable for installation of an oil-gas pipeline station and can be adjusted on site according to the site environment ofeach project. The method has huge application space and good economic benefits for leakage detection of a long-distance pipeline engineering station.