Low temperature is a major environmental stress in rice cultivating and production. The alternative oxidase 1 (AOX1) gene is potentially important for genetic engineering to increase cold adaptation. However, previous studies related to this effect have mostly focused on the dicot plants Arabidopsis and tobacco, whereas functional research on rice is limited. In this study, we cloned a rice predominant cold-response AOX1 gene, OsAOX1a. Transgenic rice plants with overexpression of OsAOX1a were obtained. We found that OsAOX1a overexpression could strongly enhance the cold growth of seedlings, especially with respect to root extension. However, growth between transgenic and control plants did not differ under normal conditions. Furthermore, the lipid peroxidation and ion leakage rate were determined after cold treatment in transgenic plants. Both factors were reduced by OsAOX1a overexpression, which revealed that OsAOX1a could reduce oxidative damage under cold stress. Taken together, our results suggested that overexpressing OsAOX1a could improve growth performance of rice under cold stress, which might be closely related to the reduction of reactive oxygen species generation and oxidative damage.