Abstract: Litter decomposition is one of the main pathways of nutrient cycling and energy flow in grassland ecosystems. Nutrient limitation is the major factor limiting production on the warm steppe. In this study, the effects of nutrient addition on litter decomposition were investigated to provide a theoretical reference for nutrient management, restoration, and construction of grassland ecosystems. On the Stipa baicalensis steppe in Inner Mongolia, the leaves, stems, and roots of S. baicalensis (Sb), Leymus chinensis (Lc) and Artemisia frigida (Af) were placed in mesh bags to measure decomposition in different treatments: CK (no fertilization), fertilization with N (ammonium nitrate), P (triple superphosphate), or NP (mixed ammonium nitrate and triple superphosphate). The residual rates of all three plants were significantly lower in the N, P, and NP treatments than in the CK, indicating that N and P addition promoted decomposition. During the decomposition process, N was released from leaves and roots at an early stage and enriched at later stages, whereas N in stems showed an enrichment-release-enrichment pattern. The leaves, stems, and roots released P and C continuously during decomposition. The residual rate of P decreased as the plant organs decomposed. The 95% decomposition time of S. baicalensis, L. chinensis, and A. frigida was 3.32-3.77 years, 2.95-3.96 years, and 2.64-4.89 years, respectively. The decomposition responses to fertilizers differed among plant organs and among plant species.