Abstract: By using open-top chamber (OTC), a pot experiment was conducted to study the effects of elevated CO2 (550 μL·L^-1), O₃ (60 μL·L^-1), and their interaction (CO₂ 550 μL·L^-1 plus O₃ 60 μL·L^-1) on the seedling dry mass and allelochemical DIMBOA content of seven winter spring cultivars. Under elevated CO₂, there existed significant differences in the shoot dry mass and DIMBOA content among  the test wheat cultivars. As compared with the control (CO₂ 370 μL·L^-1; O₃ 40 μL·L^-1), the shoot and root dry mass of cultivar Bima-1 under elevated CO₂ increased by 36.8% and 24.7%, respectively, and the DIMBOA content increased by 5.7%-184.6%. Elevated O₃ decreased the seedling dry mass except for Bima-1 and Shan-139, but increased the DIMBOA content of all the cultivars, with an increment of 0.5-3 folds. Under the interaction of elevated CO₂ and O₃, the root dry mass of all cultivars decreased, and the shoot dry mass, root dry mass, and DIMBOA content of Changwu-134 had the greatest decrement of 8.2%, 27.9%, and 35.5%, respectively. In contrast to the decrease of the DIMBOA content of Changwu-134, Yuanfeng-175 and Lankao-217, the DIMBOA content of Shan-139 increased by 84.6%. The cluster analysis indicated that both the treatments and the cultivars had significant effects on the DIMBOA content, the cultivars Shan-139, Lankao-217, and Changwu-134 under the elevated CO₂ or O₃ could be grouped together, whereas the DIMBOA content of Shan-139 in all treatments increased. These findings suggested that DIMBOA could be used as a specific indicator for resistance breeding under climate change, especially under elevated O₃ and CO₂.