The Qinghai-Tibet (QT) Plateau is considered as the "natural laboratory" of climate change in China and even in the world. Under the background of global change, the vegetation ecosystem of the QT has undergone profound changes. In this study, the spatian and temporal patterns and its driving mechanisms of NPP in the QT Plateau from 2000 to 2015 were analyzed and discussed by using gravity center and correlation coefficient models. Then, the relative effects of climate change and human activity on the process of NPP changes was quantitatively distinguished. The results show that: (1) From 2000 to 2015, the annual mean NPP in the QT Plateau showed a decreasing trend from southeast to northwest. In terms of interannual changes, the annual mean NPP showed a fluctuating upward trend in the study period, with a sharp rise in 2005 and a high fluctuation during 2005-2015. (2) The increased area of NPP in the QT Plateau (change rate >10%) was mainly concentrated in the Three-River Source Region, the northern Hengduan Mountains, the middle and lower reaches of the Yarlung Zangbo River Basin and the central and eastern parts of Naqu county, while the decreased area of NPP (change rate <-10%) was mainly distributed in the upper reaches of the Yarlung Zangbo River Basin and the Ali Plateau. (3) During the 16 years, the gravity center of NPP in the QT Plateau moved eastward, indicating that the increment and growth rate of NPP in the eastern part is greater than that in the western part. (4) The correlation between vegetation NPP and climate factors in the study area is significant. The regions with significant correlation between NPP and precipitation are mainly located in the central and the southeastern parts of the QT Plateau and the middle and lower reaches of the Yarlung Zangbo River Basin. The regions with significant correlation between vegetation NPP and temperature are mainly located in Southern Tibet, Northern Hengduan Mountains, Central and Northern QT Plateau. (5) The relative effects of climate change and human activity on the process of NPP change in the plateau have significant spatial and temporal differences with a distribution pattern of "Four Lines and Five Regions". The research results can provide theoretical and methodological supports for revealing the response mechanism of regional ecosystems to global change in the QT Plateau.