Abstract: To investigate the responses of photosynthesis in leaves of rice to light intensity atdifferent levels of elevated CO₂ concentration, Japonica rice (Oryza sativa L.) ‘Nanjing 9018’ was grown at three levels of CO₂ concentration,i.e., ambient (CK), ambient + 40 μmol·mol^-1 (T1), and ambient + 200 μmol·mol^-1  (T2) in opentop chambers (OTC), with four OTCs as replicates for each treatment. We measured leaf net photosynthesis rate (P_n) and nitrogenconcentration at different light intensities at jointingbooting, headingflowering, and milking stages. Non-rectangular hyperbola function was used to fit P_n against light intensity. P_n in T1 was slightly higher than CK at jointingbooting stage and milking stage when light intensity was low (PAR=400 μmol·m^-2·s^-1), and no significant difference was detected for all other light intensities at the three developmental stages.P_n at different light intensities and light saturated net photosynthesis (P_{n max}) in T2 was 34%-40% higher than those in CK at jointing-booting and heading-flowering stages, while there was no significant difference at milking stage. Leaf nitrogen concentrations tended to be lower in T2, while photosynthetic nitrogen use efficiency (PNUE) was significantly higher than that in CK and T1. The PNUE was enhanced with the increases of light intensity. In addition, elevated CO₂ 200 μmol·mol^-1  was beneficial to improvement of the apparent quantum efficiency at jointing-booting and heading-flowering stages.