Hailstorms occur frequently over the northeastern border of the Qinghai-Tibetan Plateau and its surroundings because of the combined geographical and meteorological features of this region. Formation and growth of the hailstones in a typical hailstorm are simulated using a three-dimensional (3-D) cloud model with hail-bin microphysics developed by the Institute of Atmospheric Physics of the Chinese Academy of Sciences (IAP/CAS). The information of the large-scale circulations for the cloud model was provided by the MM5V3 model. The results show that (1) the water content of each hailstone bin is significantly large in the "cave channels"; (2) at the initial stage of hail formation, there is another high water content region consisting of small ice particles (D < 1 mm), graupel and hail embryos (1 mm < D < 5 mm), as well as small hailstones (5 mm < D < 10 mm), around the altitude of -30 ~ -50¿C above the high water content center associated with the "cave channels"; between them there is a gap of lower water content, which means that the main mechanisms of hail formation are different in those two regions; (3) as the hail and rain fall, the maximum center at higher level drops until it merges with a lower equivalent; the larger the hail particles are, the earlier the maximum centers merge with each other; (4) during the hailstorm dissipation period the downdraft occurs in the region of "cave channels" and the "cave channels" fade; however, it is still the center of high hail water content, even though all updraft airflow turns to downdraft airflow; (5) "cave channels" are not the only regions of hailstones formation, but are nonetheless effective in the growth of hailstones, so which should be the main region of suppressing hail growth from small to large.