The forest-steppe ecotone in Greater Xing'an Range is the key area where the Greater Xing'an forest borders the Hulunbuir grassland. Due to the fragility of the ecotone, climate change and human interference have caused dramatic changes of plant community. Field surveys were conducted at the same location along the ecotone from meadow grassland to forest in 2008, 2009, 2010 and 2019 in the forest-steppe ecotone of Chenbalhu Banner in the Inner Mongolia. We evaluated the dynamics of species richness, Raunkiear life-form functional group, forage value and community biomass in a four-year study. Results showed that, compared with the average of 2008-2010, species richness significantly decreased in 2019, and more than 10 species of gramineous forages were lost; annual and biennial species increased by 4%, and perennial forbs decreased by 8%; the proportion of excellent forage decreased by 5%, while the proportion of inferior forage increased by 7%; community aboveground biomass significantly decreased by 35%. Importantly, community structure and function of the meadow grassland were more strongly affected by climate change and grazing disturbance than other sections of the forest-steppe ecotone. Based on multiple regression analysis of regional climate and grazing data, we found that annual precipitation was the main factor leading to the decline of aboveground biomass at the whole forest-steppe ecotone scale, whereas overgrazing was the overriding factor for the decline of community productivity in the meadow steppe.