Plant functional traits indicate nutrient trade-offs among organs and functions of plants to adapt to community environmental changes. Litter accumulation modifies community microenvironment by reallocating light, heat, and water in fenced grasslands. However, plant adaptive strategy in this process is still not well understood. In every August of 2015-2017, aboveground plant functional traits (i.e., plant, stem, and leaf) of Leymus chinensis were comprehensively measured in three typical grasslands in Inner Mongolia, China. The results were follows. Litter accumulation significantly increased height, aboveground biomass, stem to leaf biomass ratio, and total leaf area of plant. The length, biomass and area of leaf, internode length, and stem biomass were significantly increased in the litter accumulation treatment of the three grasslands. These traits could be considered as sensitive traits to litter accumulation. The leaf number and internode number being considered as inert traits had no significant response to litter accumulation. Plant biomass showed positive correlations with plant height and leaf biomass (P < 0.0001). Similarly, plant height exhibited positive correlations with number and length of internode (P < 0.0001). Our findings elucidate the plant adaptive strategy to environmental changes in the context of aboveground plant functional groups in fenced grasslands and provide basic data and theoretical foundation for the management of fenced grasslands.