Abstract:FFT algorithm was used to process the horizontal and vertical channel I/Q signals received from S-band dual-polarization Doppler weather radar in Lishui, Nanjing. The intensity and velocity data of two channels were obtained. We made a qualitative analysis of the differences of echo intensity and velocity data between two channels, and used the mean difference and root mean square error parameters for quantitative analysis. Comparison results show that the echo distribution obtained from I/Q data are basically the same between two channels. The difference of two channels' velocity data is small, while the difference of intensity data is large. Taking the echo data of the horizontal channel as the reference, when the echo intensity is less than 16 dBz, the horizontal channel intensity is relatively small, which may be caused by smaller acicular crystals at the cloud edge; when the echo intensity is greater than 32 dBz, the horizontal channel intensity is large, and with the increasing of the echo intensity, the intensity value difference increases between the two channels. This reflects that the heavy precipitation has more large particles, and the larger the particles, the more flattened during the landing. A certain relevance of intensity value difference and intensity between two channels is presented. This may reflects that the quantitative measurement of precipitation by the single polarization weather radar is not high in accuracy, and in the joint use of data of thetwo channels by the dual-polarization radar is expected to improve the accuracy and capability of radar quantitative measurement of precipitation.