Abstract: The study was conducted to investigate the photosynthetic characteristics of four varieties of citrus(Nai 92-1 Navel Orange, Shatangju Tangerine, Shatianyou Pummelo and Gonggan Mandarin). The results show that：1) the curve of the diurnal change in the net photosyntheticrate(Pn) of‘Nai 92-1 or Gonggan Showed only one peak, the peak occurred at 10:00, those of‘ Shatangju and Shatianyou were a typical bimodal curve, the first peak occurred 8:00 simultaneously, and the second peak occurred at 12:00 and 14:00 respectively. The maximal Pn value of Shatianyou was higher than those of others, the order of Pn was Shatianyou>Gonggan>Nai92-1>Shatangju. ‘Midday depression phenomenon of photosynthesis occurred in Shatianyou, Gonggan and Nai 92-1, nor in Shatangju. 2) There was positive relationship between Pn and the chlorophyll content of leaves, the anthocyanin was quite the reverse, and there were no marked relation between Pn and the carotenoid.