The invention discloses an automated foam concrete producing method. A device mainly consists of following units: a material bin, a frequency-variable speed regulator, a rapping machine, a gas circuit electromagnetic valve, a pneumatic valve, a liquid level meter, a liquid buffer chamber, an electromagnetic valve, a vacuum centrifugal pump, a material slurry feeding pump, a water-reagent mixing chamber, a stirrer, a foaming machine, an air compressor, a manual gate valve, a stirring slurry-making machine, a material slurry storage pot, a foam mixing apparatus, a density meter, a control cabinet, a project control system, a computer and a client software platform. The method for prepare the foam concrete in various specifications includes steps of automatically feeding materials according to preset parameters, automatically stirring the materials, performing an automatically foaming process and an automatically foam mixing process, automatically measuring a density, wherein the processes are fully-automatically (or manually) controlled and integrates technologies of material blending, slurry making, foam generating and foam mixing during preparation of the foam concrete. The method allow each process to be detected, the materials to be weighed automatically and accurately, the processes to be monitored in real time and product quality of the foam concrete to be controlled strictly.