The aim of this study was to specify the grassland vegetation turngreen date and its relationships with climate factors over the Three-river Resource region, which was used as the research area in this study. The sunshine hours, average temperature and precipitation, grassland vegetation turngreen information data from 2003 to 2012, linear trend rate, and Pearson's correlation analysis were used to systematically analyze and explore the climate change trend and its correlation relationships with grassland vegetation turngreen date over the Three-river Resource region. The results showed that the trend for grassland vegetation turngreen date was "ahead- postpone- ahead- postpone" across the region over the past 10 years. The maximum difference for vegetation turngreen date at over 4000 m above sea level and the climate factors was about 40 days. Furthermore, the most significant change trends were for grassland vegetation in alpine steppe and alpine desert areas. There was generally a good correlation between grassland vegetation turngreen date and sunshine, temperature, and precipitation 30 days before the turngreen date. However, there was a significant negative correlation between grassland vegetation turngreen date and sunshine, temperature, and precipitation in some parts of the Three-river Resource region, but there was a significant positive correlation across the rest of the region. The results showed that the grassland vegetation turngreen date was not determined by a single factor in the Three-river Resource region but was affected by a combination of sunshine, temperature, and precipitation.