Aiming at the error problem in the high frequency band of the standard frequency when the traditional bilinear transformation method is used to design the frequency weighting filter in the sound level measurement, a frequency weighting design method based on the chaotic weighted particle swarm algorithm is adopted to realize the frequency weighting Optimize the design. First, analyze and study the error source of the frequency-weighted amplitude-frequency response, and then design the optimization object and fitness function of the frequency-weighting filter according to the analysis results, and construct a frequency-weighted digital filter optimization model based on chaotic weighted particle swarms , And seek the optimal solution. The simulation experiment shows that the optimization algorithm proposed in this paper has high accuracy and the error can be controlled within 0.005dB, which meets the design requirements of the first class sound level meter in the national standard, and It is suitable for frequency weighting in sound level measurement and filter design in other fields.