In order to investigate the effect of forbidden grazing and enclosure on the alpine meadow ecosystem of the Yellow River source, this study selected the Maqin alpine meadow as the research object, and analyzed the changes of vegetation community structure and soil moisture characteristics of the alpine meadow of the Yellow River source under different forbidden grazing and enclosure conditions through field investigation and indoor experiment. The results showed that: (1) Vegetation cover and height increased with the extension of forbidden grazing and enclosure years. The species diversity index，Patrick index and species number increased and then stabilized with the extension of the closure period. The dominance index decreased and then stabilized, and the evenness index did not change significantly. In terms of functional groups, the importance of grasses and legumes increased gradually with the increase of closure years, the importance of sedge plants increased rapidly and then stabilized, and the importance of miscellaneous grasses decreased significantly. (2) The above-ground biomass gradually increased with the increase of closure years, and the below-ground biomass and total above-ground and below-ground biomass showed a trend of increasing first and then stabilizing. The effects of sealing measures on below-ground biomass were mainly concentrated in 0-20 cm. (3) The effects of forbidden grazing and enclosure on soil bulk, water holding capacity and porosity of alpine meadows in the Yellow River source were mainly concentrated in the surface layer (0-5 cm), with the increase of forbidden grazing and enclosure years, the surface soil bulk showed a trend of first decreasing and then stabilizing, the soil saturation water holding capacity, capillary water holding capacity and field water holding capacity showed an increasing trend, the soil capillary porosity and the total porosity showed a trend of increasing and then stabilizing, and the non-capillary porosity did not change significantly. Compared with the severe degradation, the 0-5 cm soil bulk density of 5 years of forbidden grazing and enclosure decreased significantly by 30.25%(P<0.05), and the saturated water holding capacity, capillary water holding capacity, field water holding capacity, capillary porosity and total porosity increased significantly by 14.44%, 18.36%, 28.19%, 18.36% and 12.09%, respectively (P<0.05). This indicates that the short-term forbidden grazing and enclosure is not only beneficial to improve the vegetation community structure of the alpine meadow of the Yellow River source area, but also enhances the water-holding function of the soil in this area.