Abstract:  There is a large number of geological disasters along the Bomi section of SichuanTibet Highway, in southeast Tibet region. The main source material of the geological disasters is loose deposits which are made by rock weathering. The topography and geological conditions are in favor of rock weathering, because of the uplift of QinghaiTibet Plateau. The difference in temperature change is another important factor for rock weathering. Compare with field observation and experiment of cylindrical rock samples, freezethaw plays a major role in the weathering of rocks in the region.