Abstract: Monthly mean maximum (T_max), minimum temperature (T_min) and daily temperature differences (△T) at 25 stations over Tibet from 1971 to 2000 are used to analyze the asymmetric change of maximum and minimum temperature in the Tibetan Plateau. The results show: The asymmetry is detectable in the whole Tibetan Plateau, and the typical pattern of asymmetry is he increase of T_max and T_min (T_min increase is bigger then that of T_max), the increase of T_max occurs mainly in summer and that of T_min in autumn and △T decrease because of obviously increasing T_min, In additon, T_min increases with increasing altitude; increase is the strongest in the region of 3000 to 4000 m, and △T tends to decrease over 4000 m.