The Living Planet Index is an indicator of the state of global biological diversity. Based on trends in 977 population time series of 161 terrestrial mammal species, we used the LPI method to set up a population trend index for China's mammal species. The index dropped by 50% from 1970 to 2010. For further interpretation and analysis the index was subdivided by biome. Index of population trends of forest ecosystem mammals decreased by 78% from 1970 to 2010. Index of population trends of prairie and desert ecosystem mammals increased by 26% from 1970 to 2010. Index of population trends of mammals in farmland and urban ecosystems grew rapidly in the late 1990s, before stabilising, and then started to drop early this century. The index decreased by 38% from 1970 to 2010. Animals’ survival strategies in response to the environment are also crucial factors that determine the fate of the species. The variation trend index based on 67 K-strategist mammals in China indicates that the population size continued to drop from 1970 to the end of last century, before it stabilised early this century. From 1970 to 2010, the population size of K-strategist species dropped by 64%. The variation trend index based on 87 r-strategists species in China indicates that the population size drastically continued to rise from 1970 to the early 1980s, before entering a cyclical fluctuation status. Population size has increased by 36% from 1970 to 2010.