Abstract: In order to solve the problems of low efficiency and excessive noise of 6MF-30 pneumatic extinguisher, the experiment and simulation were carried out under the working condition. The efficiency and SPL of the extinguisher were taken as objective parameters for optimal design and optimal variables and results were obtained by C++ programming. Taking the complex three-dimensional flow in the extinguisher into account, a three-dimensional model was built based on the multi-objective optimal structural parameters. The simulated results showed that the sound power level of the optimized extinguisher increased by 1.96% compared to original machine. However, the efficiency, outlet total pressure, outlet flow and outlet velocity increased by 17.56%, 23.96%, 11.56% and 11.33%, respectively. The combination property of the extinguisher is improved after optimization. The research can provide a reference for design of pneumatic extinguisher.