Under the influence of global warming and frequent human activities, a series of deterioration phenomena including the decreased productivity, decreased biodiversity, and ecological function degradation have taken place in the grassland ecosystem on the Tibetan Plateau. Compared with the traditional monitoring method, remote sensing technology has the advantages of wide range, rapid and continuous monitoring. Therefore, it is widely used to monitor grassland vegetation at the regional scale. Previous studies on impact factors of grassland vegetation on the Tibetan Plateau mainly focused on the climatic hydrothermal elements (i.e., temperature and precipitation). However, compared with the temperature and precipitation, the surface temperature and soil moisture have more direct effects on the physical and biochemical processes of vegetation growth. Based on remote sensing technology, MODIS and AVHRR data were collected on the Tibetan Plateau, and fractional vegetation cover was selected as the remote sensing index of grassland degradation to calculate the grassland degradation index (GDI). Then, the surface temperature and soil moisture index at the regional scale of the Tibetan Plateau were obtained to indicate the surface hydrothermal condition. Finally, the influence of surface temperature and soil moisture on vegetation was studied based on regression analysis. The results show that there were obviously spatial differences in vegetation degradation on the Tibetan Plateau from 2001 to 2017. The degradation is more severe near the Qaidam Basin and Qinghai Lake than other regions on the Tibetan plateau. The degradation is also severe in the northern part of the Himalayas, the southern part of the Kunlun Mountains, and the northern part of the Gangdise Mountains. However, the non-degraded grassland area proportion of the Tibetan Plateau increased from 50.60% to 59.00% from 2001 to 2017, which indicated that the vegetation of the Tibetan Plateau was in the direction of improvement overall. From 2001 to 2017, the grassland on the Tibetan Plateau was in mild degradation for most of the time, but in 2001 and 2015, the grassland degradation on the Tibetan Plateau reached a level of moderate degradation. The area dominated influence by soil moisture accounted for 14.04% of the whole grassland over the Tibetan Plateau through regression analysis. And the area dominated influence by land surface temperature accounted for about 36.61% of the whole grassland. Despite this, the relationship between land surface temperature and vegetation coverage affected each other, and the relationship between them was mainly negative. When the NDVI is at a lower level, land surface temperature positively affected the growth of temperate meadow.