In order to understand the flow pattern in the blower of portable pneumatic extinguisher thoroughly,computational fluid dynamics is applied and the three dimensional air flow in the blower is numerically simulated and analyzed.The control differential equations,turbulence submodel,build of three dimensional geometry model,division of the flow zone and so on are presented,which the calculating results are discussed.The simulation and analysis lay a good foundation for further improvement of the portable pneumatic extinguisher’s performance.