Abstract: The LI-6400 Portable photosynthesis was used to study the photosynthetic characteristics in leaves of Rieger begonia seedings in greenhouses. The results showed that the daily variation of net photosynthetic rate in leaves presented a bimodal curve,and there is an obvious“midday depression”phenomenon.The light saturation point was about 327μmol·m^-2·s^-1,the light compensation point was about 28.3μmol·m^-2·s^-1,the CO₂ saturation point was about 1200μl·L^-1 and CO₂ compensation point was about 60~70μl·L^-1.The photosynthesis was more sensitive to the higher temperature (>25℃).