Elymus nutans Griseb. (Poaceae: Triticeae) is a tall (shoot height usually 60-120 cm) sparse bunchgrass with broad leaves that is native to the alpine meadows of the Qinghai-Tibetan plateau, China. The study was conducted in the Hezuo Sub-alpine Meadow Ecosystem Field Station of Lanzhou University. Field experiments based on a factorial design were used to measure the effects of illumination and fertilization on the growth parameters of E. nutans to assess the ability of E. nutans to adapt to heterogeneous environments. The experiment began in April, 2006 as part of mowing trials and included eighteen 1.3 m × 0.8 m plots with a total of six treatment combinations of light and fertilization, 80 of plants per plot, 30 that were marked. The plots were separated by 0.5 m. To simulate the effects of attenuated light beneath the canopy on plant growth, green shade nets that did not fundamentally change the spectral composition of sunlight were used in this trial to create three illumination conditions similar to those in the natural environment. The three light intensities were high (100% illumination), moderate (43.5%), and low (6.74%), and plots were either fertilized with diammonium hydrogen phosphate (50 g/m²) or left unfertilized. On 10th October, we harvested 15 individual plants (five marked individuals per plot) from each treatment. Harvested plants were dug up and washed. For each plant, the number of tillers (including withered ones) was recorded, and it was separated into leaves, stem (including leaf sheaths), inflorescences, and roots. Separated plant tissues were dried in an oven (80 ℃) for 48 h and then weighed. The results show that as illumination intensities decreased from high to moderate, the above-ground biomass and number of tillers of E. nutans did not change, while plant height increased. However, as the light intensity declined to 6.74%, the above-ground biomass, number of tillers, and plant height were all reduced. The specific leaf area increased as illumination intensity was attenuated, while the relative growth rate decreased, which suggested that fertilization had no effect on either specific leaf area or relative growth rate. The differences in root-to-shoot ratios at moderate and low illumination levels were not significant, while the root-to-shoot ratios increased with the application of fertilizer under high illumination. After fertilization, allocation to leaf biomass increased while allocation to reproductive structures decreased as the light intensity was attenuated. Without fertilization, there were no significant differences in biomass allocations to either leaves or inflorescences at high and moderate illumination levels, while allocations to leaves and to reproductive structures decreased at the low illumination level. After fertilization, the stem allocations were highest at the moderate illumination intensity, intermediate at the high illumination intensity, and lowest at the low illumination intensity. Without fertilization, there were no differences in the stem allocations at the high and moderate illumination levels, while the allocation to stem tissue decreased under low illumination. The results of this study show that E. nutans is an illumination-tolerate grass species that can grow normally even when the light intensity is reduced to half of full sun exposure. Elymus nutans adapts to low-illumination environments by increasing its height and by producing large thin leaves, and its resources are balanced through altered allocations to leaf biomass, stem tissue, and reproductive structures.