Photosynthetic characteristics of leaf and calyx of Pairs polyphylla var. yunnanensis in Kunming (2100 m a.s.l.) and Zelong (985 m a.s.l.) of Yunnan Province, Southwest China were investigated in July, 2013. The results showed that the diurnal variations of the net photosynthetic rates (P_n) of leaf and calyx at the two sites exhibited a doublepeak curve with a midday depression of photosynthesis at 14:00. The maximum P_n values of leaf and calyx were observed at 10:00 and 12:00, respectively. The relatively high temperature and low relative humidity attributed to the midday depression of photosynthesis of P. polyphylla var. yunnanensis in Kunming and Zelong, respectively. The daily average P_n, maximum P_n, light saturation point and initial quantum yield of either leaf or calyx in Kunming were higher than in Zelong, whereas the lower light compensation point and dark respiratory rates of leaf and calyx were found in Kunming, which implied a higher photosynthetic capacity of Pairs polyphylla var. yunnanensis in Kunming. The photosynthetic characteristics of calyx and leaf were similar in Kunming, which showed a wide adaptability of P. polyphylla var. yunnanensis to light. The maximum P_n and light saturation point of calyx were significantly lower (P<0.05) than those of leaf in Zelong, while the significantly higher initial quantum yield was observed for calyx, which revealed a narrow adaptability to light and a high utilization efficiency to weak light for calyx of P. polyphylla var. Yunnanensis at the low altitude site. Calyx removal resulted in the decrease of fruit dry mass, and the extent of decrease in Zhelong was significantly smaller than that in Kunming.