Based on after homogenization treatment data at 81 stations over the Qinghai-Xizang Plateau(QXP) from 1971 to 2011, using of the area weighting method, the new characters of temperature over the QXP for nearly 41 years is researched. The result show that the QXP has a more significant warm mutation in 1997,lag behind the North China (1989), the Northeast China (1987) for 8 ?10 years, and later about 1 ?3 years than south and east and northwest of China. The mutation process in interior plateau has a significant relationship with terrain of the QXP,which performance as the higher the altitude,the later mutation. Besides,the warming form before and after the mutation is different, before the mutation the magnitude of warming decrease with elevation, but after the mutation the increasing tendency of temperature shows as increase with altitude,which by a 99% significant test. The maximum magnitude of the QXP warming no matter after and before mutation is in winter, and after the mutation the magnitude of warming in fall and winter had decreased, but increased in summer. Compared with the slowdown of global warming for recent 15 years,plateau after mutation showed more substantial warming,and the phase of temperature fluctuations over the QXP similar to the global temperature,both have good consistency.