Abstract: With black seed pumpkin, white pumpkin seeds and ＂Jinyou NO35＂ cucumber as test materials,at the optimunl temperature （18-20℃, CK） and warn1 （13-15 ℃） at low temperature （8-10℃） of root zone temperature conditions, the grafting cucumber and the seedling leaf net photosynthetic rate and chlorophyll fluorescence parameters of the diurnal variation were studied. The resuhs showed that compared with optimal temperature （CK）, with the loss of the root zone temperature, cucumber leaf net photosynthetic rate （Pn）, PS Ⅱ maximum photochemical efficiency （Fv/Fm） and photochemical quenching parameters （qP） and photochemical quenching （NPQ） parameters were significantly reduced. The optimum under moderate low temperature treatment, the black seed pumpkin grafting of net photosynthetic rate （Pn） and chlorophyll fluorescence parameters were higher than white pumpkin seed grafting and seedling, under low temperature stress, the black seed grafting retrograde resistance is better than that of white pumpkin seed grafting and the seedling, light energy utilization can be maintained at a relatively high level.