A rare severe convective weather process with the large hailstone, local short-time rainstorm, and thunderstorm gale occurred over northeast part of Qinghai-Tibetan Plateau from 17 to 18 August 2016. The genesis and development and propagation mechanism of the meso-small scale convective system, and the atmospheric environment field were all analyzed by using the datum of conventional observation, NCEP reanalysis, himawari-8 satellite, C and X band Doppler radar, etc. And the characteristics between hail echo and rain echo were contrasted too. The results show that:It belonged to the low-level warm advection forcing type because of the obvious lifting northward of Subtropical High over west Pacific. The Water vapor was transported mainly from the South China Sea, and the Bay of Bengal next. The starting and trigger mechanism of sever convection was the weak cold front on surface with a longer life. Convective clouds gradually evolved into mesoscale convection complex (MCC), and the convection propagated toward unstable Atmospheric stratification zone and backward inflow wind of low-level along Huangshui river valley as a whole, and the convective motion dominated by propagation due to the weak inflow wind. The river valley topography was the key to the moving and propagation path of convection. All severe convective cells had comparatively long life cycle, the strong hail cells were similar-supercells and common multi-cells, and the heavy precipitation cells belonged to the multi-cell linear convection. The strong hail cells generally developed stronger and changed more greatly than the heavy precipitation cells, such as the former had stronger echo intensity, higher organization degree, longer life cycle mesocyclone, higher echo top and echo centroid, and most echo parameters had greater changes, especially VIL (vertical integrated liquid water content). In addition, the strong echo pendency located over the weak echo region in the former cells, etc. But before the beginning of severe convection, the VIL almost increased first and then dropped, and the maximum echo intensity exceeded 60 dBZ but changed relatively small both in the hail and precipitation cells. The four positions of thunderstorm gale were generated by the strongly down-divergence flow, that was produced by greater negative buoyancy due to strong temperature-fall period of weak rain of thunder clouds evaporation in thicker dry air level, or the drag of heavy precipitation in linear convection accompanied with dry air entrainment raindrops. The characteristics in radar echo presented the sharp decline of centroid height and mid-altitude radial convergence (MARC).