The invention discloses an FSAE racing car air intake system with variable-length air intake manifolds. The FSAE racing car air intake system comprises an air filter, a throttle valve assembly, a flow limiting valve, an air intake header pipe, a pressure stabilizing cavity, air intake manifolds with the fixed length, movable air intake manifolds, a fixing support, a servo motor, a coupler, a lead screw, a sliding block, a flange, an oil injection base and oil injection nozzles, and all the components are connected in sequence. The air intake manifolds with the fixed length and the movable air intake manifolds are concentrically positioned on the two sides of the pressure stabilizing cavity. The movable air intake manifolds are concentrically and coaxially mounted in the air intake manifolds with the fixed length and jointly connected with the flange. The flange is connected with the fixing support. The servo motor is mounted outside of the pressure stabilizing cavity through the fixing support. The output end of the servo motor is mechanically connected with the lead screw through the coupler. The lead screw is connected with the flange through the sliding block. Through rotation control over the servo motor at different rotational speeds, the up-down positions of the movable air intake manifolds are adjusted, the actual length of an air inlet flow path of an engine is changed, and torque output of the engine at the medium-low rotational speed is improved.