For the Global Precipitation Measurement (GPM) Microwave Imager (GMI), the radio frequency interference (RFI) correction algorithm of the land-surface brightness temperatures is proposed, and the comprehensive index method of polarization corrected temperature-scattering index (PCT-SI) suitable for the GMI instrument is proposed. The rainfall intensity in Jiangsu and its surrounding areas after the landing of Typhoon In-fa (2106) is retrieved, and the retrieval data is compared with the detection data of Dual-frequency Precipitation Radar (DPR) in the same period. And also, the retrieval accuracy of near-surface rainfall intensity before and after RFI correction is compared. Furthermore, the accuracy of the rainfall intensity retrieval algorithm and the effectiveness of the RFI correction algorithm in improving the retrieval accuracy are validated by application in Typhoon Muifa and a Jianghuai cyclone process. The results show that the high-frequency observation of GMI is closely related to the precipitation rate. The atmospheric scattering index is obtained by fitting the brightness temperature of 89.00 GHz channel with the low-frequency combination; the larger the scattering index, the greater the rainfall intensity. The RFI signal has a significant impact on the retrieval of near-surface rainfall intensity from microwave measurements, and the proposed correction method can effectively correct the GMI observation data contaminated by RFI on the land surface. The results are helpful to reveal the correlation between multi-channel brightness temperature data of microwave sensors and precipitation intensity, improve the accuracy of microwave retrieval of land-surface precipitation, and provide reference for retrieval and prediction of land-surface precipitation.