The Qingpu CINRAD/SAD radar and the Nanhui WSR88D radar, located in Shanghai, are of different models, and different dualpolarisation technology upgrade schemes are adopted, so there is a certain data deviation between the two radars in actual business operation. In order to quantitatively evaluate the detection performance of the radars, analyse the main sources of differences in radar data, and improve the application of the data of the two radars in business forecasting, algorithm research and other aspects, a total of 3933 times of data in 30 processes are selected in the common detection area from July to September 2022 and June 2023. The data set includes typical weather processes such as hail, typhoons, and plum rains. The data are divided into stable precipitation and convective precipitation, and are compared according to intensity classification. We mainly use the data space matching method based on radars at different positions, the horizontal structure of reflectivity (ZH), differential reflectivity (ZDR), correlation coefficient (CC) and differential phase shift (ΦDP) and their variation trend with azimuth, the variation trend of radar sensitivity with elevation and the quantitative statistics of ZH and ZDR deviation for evaluation. The results show that the ZH observations of the two radars are close to each other. The ZDR, CC and ΦDP of the Qingpu CINRAD/SAD radar are more affected by the ground features and lightning rods, and are unstable with the change of azimuth, meanwhile, the nonmeteorological echo filtering effect of the Qingpu CINRAD/SAD radar is worse than that of the Nanhui WSR88D radar in the lower layers. The Nanhui 88D radar utilises azimuth superresolution technology to obtain a more refined echo structure. The Nanhui 88D radar only installs a lightning rod on the top of the radome, which is basically not affected by the lightning rod. The radar parameters are more stable as the azimuth changes. The deviation of ZH and ZDR of the two radars is larger in the area where the ZH is greater than 40 dBz. For stable precipitation of 15-25 dBz, the deviations of the ZH and ZDR of the two radars are small. Through calculation, the average deviation of ZH is 0.9 dB and ZDR is -0.14 dB. Based on the data of typhoon, hail, shortduration heavy precipitation and Meiyu precipitation, we quantitatively evaluate the differences between the two Sband dual polarisation weather radars in Shanghai from different aspects, providing a reference for subsequent algorithm improvements and data correction.