A mean value model of the 1.5L gasoline engine was established. It mainly consists of fuel film model, transient fuel film compensation model and dynamic output model. After the validation of steady state, the power and economic performances were analyzed with NEDC drive cycle. Together with engine operating points, special attention was such key parameters as paid to engine speed, engine torque and fuel consumption. The dynamic model is validated. The air-fuel ratio fluctuation was studied to validate the fuel film model.