Grasslands have been recognized as important source of biomass for biofuel production recently. In this study, our objective was to assess the potential supply of biofuel production of main plants in Leymus chinensis steppe in Xilin River Basin,Inner Mongolia. And we also wanted to understand how will the caloric value respond to ash content and other mineral elements composition. We charaterizing their correlationships. We determined the caloric value(Testing by the Parr6300 calorimeter produced by U.S), ash content(Testing by the quick determination method), concentrations of carbon(Testing by the K₂Cr₂O₇-H₂SO₄ oxidation method), nitrogen(Testing by the Kjeldahl procedure) and mineral nelements(Testing by Microwave Digestion-ICP) of fifteen native plant species. These tested species, which were selected in August 2009, are most commonly found in Leymus chinensis steppe and account for more than 80% of totoal community biomass. The results showed that the variables determined varied among the fifteen species to different extent. The caloric value ranged from 16.19 MJ/kg in Kochia prostrate to 20.99 MJ/kg in Caragana microphylla, with a mean value of 18.76 MJ/kg which is greater than that of worldwide terrestrial plants. And the rank ordering of the fifteen species was Caragana microphylla Lam>Poa annua L.>Stipa baicalensis Roshev>Agropyron cristatum L>Achnatherum sibiricum L>Aneurolepidium chinense Kitag>Cleistogenes squarrosa Keng. >Artemisia commutata L>Achnatherum splendens Nevski>Potentilla tanacetifolia Willd>Artemisia sievrsiana willd>Artemisia frigida Willd>Setaria viridis L>Convolvulus ammannii L>Kochia prostrate L. The ash, which ranged from 3.26% in Achnatherum splendens Nevski to 20.25% in Convolvulus ammannii L, indicated significantly difference at level 0.05 among the fifteen species. And the number of fifteen species was Convolvulus ammannii L> Kochia prostrate L.>Artemisia frigida Willd>Artemisia sievrsiana willd>Potentilla tanacetifolia Willd>Setaria viridis L> Agropyron cristatum L> Aneurolepidium chinense Kitag> Poa annua L>Cleistogenes squarrosa Keng>Artemisia commutata L>Achnatherum sibiricum L>Caragana microphylla Lam>Stipa baicalensis Roshev>Achnatherum splendens Nevski. Calorica value of leguminous plants (Caragana microphylla Lam) was higher than perennial gramineous plants(Caragana microphylla Lam, Poa annua L., Stipa baicalensis Roshev, Agropyron cristatum L, Achnatherum sibiricum L., Cleistogenes squarrosa Keng), and the caloric value of Kochia prostrate L. was the lowest. Pearson's correlationship analyses revealed a negatively significant correlation between caloric value and ash content (P < 0.01), while a positively significant correlation btween caloric value and carbon concentration (P < 0.01). However, there were no consistent relationships found between caloric value and concentrations of mineral elements. The greater caloric value of the steppe grasses showed in this study, compared with that of switchgrass which is one of most promising biofuel crops, indicates provides an evedent that the grassland has a potential for bioenergy production, especially leguminous plants and perennial gramineous plants. Such as Caragana microphylla Lam, Poa annua L., Stipa baicalensis Roshev, Agropyron cristatum L, Achnatherum sibiricum L, Cleistogenes squarrosa Keng and so on.