Abstract: The population of Elymus sibiricus was sprayed at the jointing or booting stage with various concentrations of paclobutrazol or chlormequat chloride. The biomass structure, energy accumulation and distribution, and the lodging rates of populations were determined and analyzed at the full flowering stage. After spraying growth inhibitor, there was a highly significant effect between traits and biomass of components, which led to a highly significant influence between aboveground and underground biomass structure (P<0.01). Growth inhibitor had significant effects on the energy value of leaves and stems, but little effect on energy value of roots and inflorescence(P＞0.05). A highly significant influence was found between biomass and energy distribution of populations, with the influence in the sequence inflorescence＞stem＞leaf＞root. At the jointing stage, application of chlormequat chloride was beneficial for increasing biomass and energy in the stem and leaf but at the booting stage, it was beneficial only for biomass and energy in the stem. Application of paclobutrazol helped distribute biomass and energy to the inflorescence and at the jointing stage the effect was significantly stronger than at the booting stage. Growth inhibitors may significantly elevate root biomass and reduce the lodging rate of populations. Paclobutrazol could be applied at the jointing stage for seed production, while chlormequat chloride could be sprayed at the booting stage for forage production. At the booting stage, 200 mg/L chlormequat chloride increased fresh grass yield by 10.22%, and 200-600 mg/L paclobutrazol at the jointing stage significantly raised potential seed production.