Abstract: Huaihe River Basin is a typical area in East Asian monsoon region with unique characteristics, and is also the most representative farmland ecological region in China. The aboveground biomass (AGB) can not only represent the current situation and carrying capacity of farmland resources, but also provide basic data for the study on carbon cycle in farmland ecosystem.Based on BEPS model and GLOBMAP LAI products, the AGB in the Huaihe River Basin in recent 38 years was estimated, and its spatial and temporal distribution characteristics were analyzed. The results show that: 38 years mean daily AGB in Huaihe River basin varied with single peak curves, and the peak occurred at 217 d (5 August (common year)/ 4 August (leap year)). The annual average AGB rises in volatility, from 836.8 g·m^-2 in 1981 to 983.3 g·m^-2 in 2018. The spatial distribution of annual average AGB increase obviously from 1980s to 2010s. AGB was high in the South and low in the north, and also high in the western part of the Huaihe River basin. The annual average AGB_max rises in volatility, from 2111 g·m^-2 in 1981 to 2610 g·m^-2 in 2018. The study can provide reference for the analysis of spatial and temporal variation of biomass on a large scale in the future, and also provide data for in-depth study and long-term monitoring of farmland ecosystem.