Forage land construction (FLC) refers to the cultivation and construction of artificial grasslands through agricultural techniques such as replanting, fertilization, and irrigation. The constructed forage land can be used for grazing and can also serve as an important source of supplementary feeding such as green fodder and silage. The FLC is thus of great significance for the sustainable development of animal husbandry and the protection of grassland ecology. However, studies on FLC from the perspective of herder households, the direct and major grassland users, are not yet sufficient. It is not conducive to grassland ecological governance under the current land tenure system. Using herder households' field survey data collected by the authors in 2021 from Urad Middle Banner of Inner Mongolia, China, this study applied a multivariate ordered logistic model (MOLM) to explore the impacts of FLC on grassland vegetation coverage (GVC). Based on the NDVI of typical Gachas, the impacts were further evidenced with ArcGIS spatial analysis method. The results show that: (1) 61.2% of herder households have constructed forage land. Among which, households with elder head and smaller grassland areas being more inclined to construct forage land; (2) FLC is generally conducive to improving GVC. At herder household level, GVC of households with forage land is significantly higher than that of households without forage land. At Gacha level, the higher the proportion of households with forage land, the better the Gacha's GVC, and the higher the NDVI values; (3) The FLC has heterogeneous impacts on GVC in terms of forage land scale. The GVC is the highest when forage land accounts for 0.6% of the managed grassland area or is within 1-1.67 hm². When the forage land area is less than 1hm², the positive impact of supplementary feeding on grassland ecology is offset by the expanded breeding scale of herders, resulting in degraded grassland vegetation. When the area of forage land is more than 1.67 hm², the GVC of herder household doesn't change significantly. The results to some extent support the development theory of grassland and animal husbandry in pastoral areas of "protecting the large natural grassland area with limited constructed forage land (Yixiao Baoda in Chinese)". Considering the vast area, diverse types, and varying conditions of natural grasslands in China, adapting to local conditions to determine the reasonable proportion of FLC is the key for grassland ecological conservation through FLC. The study is expected to provide practical reference for FLC and grassland ecological restoration in the farming-pastoral ecotone of northern China.