The tubers of Scirpus planiculmis and S.nipponicus are the main food for migratory Siberian Cranes Grus leucogeranus at the Momoge National Natural Reserve (MNNR) of Jilin Province, Northeastern China. During 15-25 September 2010, we sampled tubers of these two species at 470 points evenly distributed at 100 m intervals along 20 transect lines at Etoupao wetland, the area of the highest concentration of migratory Siberian cranes at MNNR. Six different methods of spatial interpolation including inverse distance weighting (IDW), four radial basis functions (RBF) and ordinary kriging (OK) were employed to simulate the Scirpus tuber density in the study area based on the field sampling data. According to the results of the cross-validation and spatial distribution, the spline with tension of RBF is the most optimized method with the highest accuracy. The results of this method showed that the mean tuber density was 46.0±44.3 no./m². Areas with tuber densities < 25, 25-100, and > 100 /m² occupied 41.7%, 45.9% and 12.4% of the study area, respectively. The results provide basic, yet critical, data for determining the relationship between Siberian cranes and tuber availability, and predicting the environmental capacity of Etoupao wetland for supporting migratory Siberian cranes.