Sand burial and water supply are the key ecological factors that affect plant survival and growth in Mu Us sandland. Caragana korshinskii and Hedysarum laeve are two dominant semi-shrub species distributed in this area. Experiments were conducted under controlled conditions to investigate the effects of sand burial and water supply on seedlings survival and growth of these two species. The results showed that appropriate sand burial (0.25H-0.50 H burial, H is the hight of seedling) and water supply (50 mm/month for C. korshinskii, 75 mm/month for H. laeve) could promote seedling growth of two species, whereas over sand burial could inhibit seedling growth, and even resulted in seedlings death. Seedlings of C. Korshinskii had a higher RGR and NAR under 50 mm water supply and 0.25H, 0.50 H sand burial regimes, while H. laeve had higher RGR and NAR under 75 mm water supply and 0.25H, 0.50 H sand burial regime. However, all seedlings died under 1.0 and 1.25 H sand burial regimes. The ratio of root/shoot was high when water supply was low and sand burial was shallow for two species; when water supply was high, the ratio of root/shoot was high for C. korshinskii under the deepest and the shallowest sand burial regime, while it was high under the shallowest sand burial for H. laeve.