The invention belongs to the gasoline engine field, in particular to an air management system of a supercharger gasoline engine, which comprises an air compressor, an intercooler, a main turbine and a double-effect turbine; in the medium or high speed operating condition, the double-effect turbine is serially connected behind the intercooler; the a cylinder and a main turbine are serially and sequentially connected behind the double-effect turbine; the double-effect turbine acts the turbine cooling effect; in the low speed operating condition, the intercooler, the cylinder and the main turbine are serially connected, and then the double-effect turbine is serially connected; the double-effect turbine acts the effect of improving the output torque. The air management system of a supercharger gasoline engine has the advantages of realizing the functions of turbine cooling and the double turbo supercharging, well controlling the inlet gas temperature, allowing higher supercharging ratio and improving the low-speed torque, adopting different operation modes under the high, medium and low rotation speeds, enabling the operation state of the system to be optimized under different operating conditions.