This paper studied the effect of 50~200 μmol·L^-1 exogenous melatonin（MT）on the plant growth, photosynthesis, antioxidant system of eggplant (Solanum melongena L.) seedlings of ‘Huqie 081’ under low temperature stress ［(10±1)℃/(5±1)℃, day/night］ using substrate culture. The results showed that: (1) under low temperature stress, the plant height, stem diameter, shoot fresh weight and root fresh weight, chlorophyll content, net photosynthetic rate (P_n ), stomatal conductance (G_s) and transpiration rate (T_r) were decreased significantly, the malonadehyd (MDA) content, superoxide radica production rate (O^-·₂) and hydrogen peroxide (H₂O₂) content in leaves of the eggplant seedlings were increased significantly. (2) The activities of superoxide radical (SOD), perxidase (POD), catalase (CAT), ascorbate peroxidase (APX), glutathione (GR) and dehydroascorbate reductase (DHAR), ascorbic acid (AsA) and glutathione (GSH) contents were increased markedly, proline and soluble protein contents were enhanced remarkably. Exogenous MT significantly reduced MDA content, O^-·₂ producing rate and H₂O₂ content , and raised the activities of SOD, POD, CAT, APX, GR and DHAR, AsA and GSH contents, proline and soluble protein contents under low temperature stress. These results suggest that exogenous MT can effectively alleviate the low temperature damage and improve the resistance of eggplant seedling under low temperature stress.