Abstract: The data for temperature，relative humidity，and yield of watermelon are gained under three planting modes in plastic shed ．The temperature and relative humidity are propitious to the growth of watermelon on three weather states in the planting of three stands and two floors，in Shanghai on springtime．The temperature above 40℃ is not propitious to the growth of watermelon fruit．The suitable average temperature of a day is 27℃ for watermelon．the changes are from 15℃ to 38℃ ，the suitable relative humidities are from 75％ to 80％．