The invention discloses a method for promoting leguminous plant growth by using arbuscular mycorrhizal fungi and rhizobium, which can improve the yield and quality of leguminous plant grassland without damaging a grassland ecosystem. In the method, by inoculating the arbuscular mycorrhizal fungi inoculant and rhizobium, nutrient absorption of leguminous plants can be promoted, the diversity and stability of communities can be improved, the space soil fertilizer utilization rate can be increased, leguminous nitrogen fixation can be promoted, host plants can be assisted in absorbing soil nutrients, soil can be loosened, soil hardening can be eliminated, soil structures can be improved, and the dosage of chemical fertilizers and pesticides can be reduced; loss of artificially applied chemicalnitrogen fertilizer is prevented, environmental pollution is reduced, and ecological safety is guaranteed; compared with chemical fertilizers, the utilization rate is higher, the acting time is long,the content of organic matter and nutrients in soil can be increased, fertility soil is improved, emission of greenhouse gas is reduced, and therefore the virtuous cycle of a grassland agricultural ecological system is promoted. The method is suitable for application and popularization in the technical field of pasture planting.