Abstract: Aim A new type of fan with tandem cascades was put forward to meet the needs of armoured vehicles for the high air pressure and larger air flow. So the pressure and flow will be prompted. Methods The fluid field of this fan was computed by use of Euler equation, and the skin grid was constructed before calculation for high precision. Results The separation extent is low on the back of the profile, but the degree of curvature is bigger, and the mach curves of cascades are plump so that the static pressure is high. Conclusion The theory results will support the subsequent research on experiment.