The invention provides a foam generator for compressed gas. The foam generator comprises a foam generator shell, a liquid nozzle, a turbulator and a compressed gas entrance, wherein the liquid nozzle is used for controlling flow rate of foam extinguishing agent premixed liquid entering the foam generator; and the compressed gas entrance is used for controlling flow rate of compressed gas entering the foam generator. The foam generator is used for enabling the foam extinguishing agent premixed liquid entering the foam generator to form rotating fog liquid, and be impacted with and mixed with the compressed gas entering the foam generator to form foam. Compared with the prior art, the foam generator for the compressed gas provided by the invention can greatly improve the mixing capacity of foam liquid and high-pressure gas, so that the ejected foam has the advantages of high kinetic energy, long ejecting distance, uniform and stable foam, high fire-extinguishing speed, high fire-extinguishing strength, long fire-retarding time, high fire-extinguishing efficiency, small use amount of foam and the like.