Tropical Rainfall Measuring Mission (TRMM) 3B43 rainfall products during the period of 1998~2016 are evaluated via monthly and yearly precipitation data from 56 observational stations over the Yangtze River Delta (YRD). The results are as follows: (1) annual rainfall increases gradually from northwest to southwest and monthly precipitation surges sharply, owing to rainband's abrupt pushing north caused by the westward and northward extension of Western Pacific Subtropical High, to 200 mm/month in July; (2) only seized by the TRMM, the developing process of ChunAn precipitation center synchronizes with monthly precipitation series that may recycle throughout the year; (3) 3B43 data are inclined to overestimate precipitation but performs the best (relative bias ranging within -10~10%) at most parts of the YRD zone; and its correlation coefficient with observation is 0.88 in annual scale; for monthly scale, CC peaks in March (0.96) and reaches the bottom (0.79) in August; (4) no evident connection between CC and elevation is found in the 3B43 annual rainfall products which estimate precipitation better upon urban land. This paper is of importance in understanding the impacts of complex topography and landcovers on the precipitation assessment in a river delta scale.