The effect of warming on plant community structure and species diversity was studied in the Stipa brevifora desert stppe by using infrared radiation method to simulate global warming. The results showed as follows: Compared with control (CK), the soil temperatures increased by 0.39, 0.38 and 0.31 ℃ at depths of 10, 20 and 30 cm, respectively, under the warmed plots in the whole plant growing season of 2012, whereas soil water content was decreased 0.76%、0.73%、0.60% in different soil depth, respectively; The change of plant community height, density, frequentness and diversity was found due to the elevated soil temperature and the decreasing soil water content. The structure of plant community has also been changed by warming. The warming significantly decreased the important value of Artemisia frigida, but it significantly increased the important value of Convolvulus ammanii. In addition, warming significant increased the coverage of grasses, whereas it significantly increased the coverage of forbs. No change was detected for semi-shrub and annual-biennial. Warming significantly decreased plant community above- and below-ground biomass allocation pattern transferred to deep soil layers. The below-ground biomass of 0-10 cm soil layers was lower in warming than in control, but below-ground biomass of 10-20 cm was higher in warming (11.55%) than in control (9.16%) and 20-30 cm was higher in warming (7.22%) than in control (4.77%). Warming led to the transfer of below-ground biomass from upper layer to lower layer. Warming significantly decreased Shnnon-Winener index, but significant increased Pielou index by elevated temperature. Warming significantly increased evenness of desert steppe, whereas no change on plant species diversity.