This paper takes G4-73 centrifugal fan as the reference model. A practical parametric software platform was developed with VB Programming languages and Fluent software. Numerical simulation based on k-e turbulence model in the same flow rate was taken using the platform. The results show that the total pressure and efficiency of fans will be ideal when the blade angle take 45 degree, which is the design value. However, the best impeller width gotten from numerical simulation is smaller than the design value, that is, 18.5 cm is the most suitable value. The conclusion is of great significance for the subsequent optimization and reconstruction of fan.