The Ecological Protection and Restoration Program (EPRP), initiated in 2005 in the Three-River Headwaters (TRH, the headwaters of the Yangtze, Yellow, and Lantsang rivers) region, is the largest project for nature reserve protection and reconstruction in China. This massive effort was expected to improve the trade-off between grassland productivity and grazing pressure in the region. However, the impacts of EPRP on forage supply and livestock carrying capacity remain poorly understood. Using the Global Production Efficiency Model and grazing pressure index, we investigated the influences of the EPRP by comparing the grassland yield and grazing pressure index before (1988-2004) and after (2005-2012) implementation of the program. Vegetation cover, represented by the annual maximum Normalized Difference Vegetation Index (NDVI), increased by 11.2% after implementation of the EPRP. The increase of NDVI, together with increasing temperature and precipitation, led to a 30.3% increase of the mean annual grassland yield in 2005-2012 relative to that in 1988-2004 (694 kg ha(-1) vs. 533 kg ha(-1) dry matter). We show that grazing pressure was largely alleviated by the EPRP due to increased grassland yield and decreased livestock number. This was indicated by a 36.1% decline of the grazing pressure index. The effects of the EPRP varied spatially. As examples, there were larger increases of grassland yield in the southeast of the region dominated by alpine meadow and greater reduction of grazing pressure in the central and eastern parts. Nevertheless, the ecological effectiveness of the EPRP may vary with the measures used and is indicated to be coupled with climate change. This calls for more detailed comparison and attribution analyses to predict the ongoing consequences of the EPRP in order to attain sustainable implementation of restoration practices in the TRH region.