To reveal the response of the soil microbial biomass carbon pool (MBCP) in alpine meadows to litter inputs, the present study was conducted to simulate the effect of litter inputs on MBCP in ungrazed, lightly grazed, and moderately grazed alpine meadows. In this study, four level gradients, T0 (0 g·C·m²), T1 (1.39 g·C·m²), T2 (3.48 g·C·m²), and T3 (6.97 g·C·m²²), were set up in alpine meadows as the research object, and the effects of different levels of litter inputs on MBCP in ungrazed, lightly grazed, and moderately grazed alpine meadows were analyzed. The results showed that with increasing litter input, S-β-XYS, S-β-GC, S-FDA, S-DHA, and CBH all had maximum values at T3. Soil S-β-XYS, S-β-GC, GOD, and S-DHA under light grazing were higher than those under ungrazed and moderately grazed. The peak values of S-β-XYS, S-β-GC, and S-DHA were at T3, which were 16.87 U/g, 41.09 U/g, and 21.01 U/g, respectively. MBCP was higher in lightly grazed than in ungrazed and moderately grazed at different levels of litter input and peaked at 18.72 g/ m² at T3. Structural equation modeling showed that soil microbial biomass in ungrazed alpine meadows was significantly positively correlated with MBCP, and enzyme activities were negatively correlated.