The automatic drain in aluminium compressed air pipeline is a device for automatically removing condensate from the low places of pipeline, oil-water separator, air tank and the bottom of various filters. It can be installed in places where it is inconvenient to drain water manually, such as high, low or narrow places, and can effectively avoid the problem of compressed air being recontaminated by condensate due to the forgetfulness of manual drainage. Overall, the automatic drain in aluminium alloy compressed air pipeline is a convenient and effective device that can automatically remove condensate from the pipeline, keep the compressed air system clean and dry, and improve the service life and working efficiency of the equipment.