Climate models predict that the atmospheric CO₂ concentration will double and atmospheric temperatures will increase 1.8–4.0°C globally by the end of this century. These changes will influence the growth of both crop plants and herbivores. The effects of elevated CO₂ and temperature on the twospotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae), feeding on maize, Zea mays L., were examined in environmentally controlled chambers. Elevated CO₂ decreased N content and increased total nonstructural carbohydrate (TNC) content and the TNC:N ratio in maize leaves. Developmental time of larvae, protonymphs, deutonymphs, and the entire immature development of T. urticae was reduced at elevated temperatures, while elevated CO₂ slightly mitigated the effects of elevated temperature on developmental time. The fecundity of T. urticae declined under elevated CO₂ and temperature. Tetranychus urticae had lower net reproductive rate and shorter generation time at elevated temperatures, regardless of CO₂ level. These results indicate that elevated CO₂-mediated decrease in nutritional quality of maize leaves extends the development time of T. urticae. Taken together, with the increase of CO₂ and temperature, the growth and development was accelerated for T. urticae feeding on maize, but its fecundity declined, which will decrease the T. urticae damage to maize for each generation. However, the number of generations will increase in high accumulative temperature regions, which may exacerbate T. urticae damage to maize. Thus, more integrated studies and realistic experimental designs are needed to predict the maize–T. urticae interaction under future climate change scenarios.