Abstract: In order to improve the efficiency of portable pneumatic extinguisher, the 6MF-30 type extinguisher was test and optimized. The efficiency of the extinguisher was taken as the objective parameter for optimum design and optimal variables combination was got using C++ programming. A three-dimensional model was constructed based on the objective optimal structural variables and the influence factors of the extinguisher performance were analyzed by using FLUENT of CFD software. The results showed that the total pressure at outlet, the volume flow rate and the efficiency of the optimized extinguisher increased by 8.95%, 5.30% and 11.53% respectively. The method proposed can provide a reference for the design of extinguishers.