The invention provides a vacuum premixed burner with a small orifice throttling device. A high-temperature-resistant air outlet cover plate in the burner is mounted in a groove which is formed after a front barrel and a rear barrel are welded; a soldering seal bottom plate is welded on the other end of the rear barrel; a fuel duct and an oxygen duct are welded on the rear barrel; a fuel outlet sleeve is welded on the fuel duct which extends into the interior of the rear barrel; a fuel throttling joint and an oxygen throttling joint are respectively welded on the fuel duct and the oxygen duct; compression plug screws are respectively mounted on the fuel duct and the oxygen duct; and a ceramic pipe fixing block is welded on the front barrel. As throttling orifices are integrated in the oxygen throttling joint and the fuel throttling joint, a separate throttling valve is omitted so that the whole burning system is small in space and mass, low in cost and high in reliability.