Abstract: Helmholtz muffler can effectively suppress low-frequency noise in a specific frequency range. In this paper, a Helm-holtz muffler is designed, which can reduce the noise at 145 Hz. However, the muffler has narrow muffling band-width, which needs to be increased under the condition of keeping the same resonant frequency. The genetic algo-rithm is chosen to deal with Helmholtz muffler, and the structure parameters of the muffler are optimized. The sim-ulation of the optimized structure is carried out, and the results show that the muffling bandwidth is broadened from 32 Hz to 86 Hz. However, the experimental results show that the muffling bandwidth of the optimized muffler increases from 55 Hz to 105 Hz, i.e. broadened by 91%. This proves the feasibility of the optimized results, which achieves broadband muffling, and provides a reference for the optimization design of mufflers.