Abstract: High temperature stress could seriously inhibit the growth and development of potatoes, leading to the decline of production and cause serious economic losses. To study heat resistance mechanism of potatoes, we analyzed the effect of potato seedlings’ growth conditions and some physiological indices under high temperatures. [Method]We tested the superoxide anion(O2-),malondialdehyde(MDA),hydrogen peroxide(H2O2) and proline(PRO) contents and the activities of superoxide dismutase(SOD), peroxidase(POD), and catalase(CAT) of potato seedlings under the high temperature treatments. The phenotypic changes before and after the high temperature treatment were also recorded. [Result]The results indicated that the high temperatures have certain effects on plant shape, leaf size and growth conditions. The contents of SOD was rising first and then decreased; values of POD and CAT were decreased first and then increased. Meanwhile, the contents of O2-, MDA, H2O2,and PRO were all increased during the examination period. [Conclusion]In summary, the accumulation of reactive oxygen species and increased membrane oxidation in potato seedlings were the reasons that may cause the damages to potatoes under high temperatures.