Based on the statistical data of animal husbandry and remote sensing data of grassland coverage, we analyzed the spatial distribution and occurrence trend of rodent pest in grassland and estimated biomass loss in grassland ecosystem caused by rodent pest by the method of ecological energetics from 2000 to 2010 in China. Results showed that the occurrence areas and occurrence intensity of rodent pest and the biomass loss of grassland showed general upward trend, and the average annual loss of grassland caused by rodent pest was about 11.815 4 million tons from 2000 to 2010. The grassland loss between years varied widely and in 2006 there was the largest loss of 25.372 3 million tons. The grassland loss in descending order for regions was Southwest, Northwest, North and Northeast, and among the provinces, the most serious loss occurred in Tibet where the average annual loss accounted for 38.09 % of the national total.