Internal flow field and pressure field of a centrifugal fan was simulated by means of Fluent software. The worm tongue was found to be the main noise source through spectral analysis. According to the numerical simulation results, the tongue structure was improved and re-simulated. The result shows that the A-weighted sound pressure levels of the noise at the worm tongue and the outlet decrease by 6.1 dB and 1.9 dB respectively after the improvement. Changing the clearance between the tongue and the blade tip and the inclination angle of the tongue can effectively reduce the noise of the centrifu-gal fan.%为了降低离心风机的噪声，以某径向叶片离心风机为对象，利用Fluent软件对其内部流场与压力场进行了建模与计算，通过对计算结果的频域分析，确定了蜗舌为主要噪声源。对蜗舌结构进行了改进并重新计算。对比前后的计算结果，显示了改进后的风机在蜗舌及出口处的A计权声压级比原型机分别降低了6.1 dB和1.9 dB。由此证实，通过改变蜗舌间隙和倾角参数能有效降低离心风机的噪声源强度。
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