Abstract: In this paper, the effects of nitrogen fertilization on biomass, caloric value and ash content of Helianthus tuberosus L. was studied. The experiment was carried out in the abandoned land in Xilin River Basin of Inner Mongolia in 2010 with 5 nitrogen treatments, 0, 2.5, 5, 7.5 and 10 g/m2. The caloric values, ash contents and dry biomass of leaves, stems, tubers and roots were measured after the harvest. The results show the biomass, energy accummulation amount and caloric value are improved by the use of nitrogen fertilizer, and the best N treatment is 57.5 g/m2. The caloric values are in order of root＞stem＞tuber＞leaf, the energy accummulation amounts are tuber＞stem＞leaf＞root, and the ash contents are leaf＞stem＞root＞tuber.