Disclosed is a cement backward flow preventing arch breaking air tap used for the cement supply system of a stabilized soil mixing plant; wherein two small cones are butt welded on an elbow which is welded on the wall of a large cement cone; and the wall of the large cement cone is provided with a processing hole, and the hole at the wall of the large cement cone is welded with a nut which is communicated with an air circuit system; when the arch breaking with air is stopped, although the compressed air is stopped, owing to the function of the elbow and the small cone, the solenoid valve damage caused by cement backward flow can be prevented; and the cement backward flow preventing arch breaking air tap used for the cement supply system of the stabilized soil mixing plant has simple structure and has the function of preventing the cement from backward flow.