Abstract: The chilling injury index and physiological characteristics of watermelon from Hebei province under different low temperature were studied. The result showed that the chilling injury index differences were obvious among the varieties. The highest one was Chongchaxiongfeng and the lowest was Jingxinwang among chilling injury index of varieties. With the decrease of temperature the activity of Superoxide dismutase (SOD), peroxidase (POD) and malondialdehyde (MDA) content were gradually increased. Activity of SOD at 8℃ had high significant positive correlation with the cold-tolerance of the varieties. MDA content had high significant negative correlation with the cold-tolerance of the varieties at 8℃, 15℃ and 25℃.