The diurnal and seasonal climatology of the precipitation depth over the Tibetan Plateau and its downstream regions is investigated using the data of Tropical Rainfall Measuring Mission (TRMM) precipitation radar (PR) measurements from 1998 to 2007. Results demonstrate that both convective and stratiform precipitation depths are smaller in Tibet than in its downstream regions. The convective precipitation depth in the East China Sea region is smaller than that in the Yangtze Plain, while the stratiform precipitation depth is similar for these two regions. The diurnal amplitude of convective precipitation depth is large over both the Tibetan Plateau and the Yangtze Plain, while it is small over the East China Sea. The diurnal cycle of stratiform precipitation depth is not significant over these regions. There are prominent seasonal variations of convective precipitation depth and stratiform precipitation depth over the Tibetan Plateau, the Yangtze Plain, and the East China Sea. Both convective and stratiform precipitation systems gradually deepen from winter to summer, and vice versa. The horizontal distribution of precipitation depths over the Tibetan Plateau and its surrounding regions shows a close relationship with the spatial pattern of surface rainfall, i.e., the area with more surface precipitation is generally corresponding to a large precipitation depth. There is a significant difference between the convective and stratiform precipitation depths, and the precipitation depth is generally larger for convective systems than for stratiform systems. The precipitation depths during the daytime and the nighttime over the Tibetan Plateau and its surrounding regions are similar, however, they have clear seasonal variations, which are consistent with the seasonal variation of the climate precipitation systems.