Rising tropospheric ozone (O₃) concentration and global warming caused by anthropogenic activities have severely affected crop growth. In this study, japonica rice Nanjing 9108 was used as the test material based on the free-air O₃ concentration and temperature enhancement (O₃-T-FACE) system. The O₃ concentration were set to ambient O₃ concentration (A) and 1.5 times ambient O₃ concentration (E); the warming treatments were set to ambient temperature (CK), canopy temperature + 1.5℃ (+1.5) and canopy temperature + 2℃ (+2), respectively. The photosynthetic rate and chlorophyll content of rice leaves were measured at the middle and late grain filling stage to clarify the combined effects of elevated O₃ concentration and warming on photosynthesis. The results of two years experiments showed that compared with ambient O₃ concentration, elevated O₃ concentration had no significant effect on the photosynthetic indexes of rice leaves at the middle grain filling stage, but significantly decreased the saturated photosynthetic rate (A_sat), stomatal conductance (g_s) and chlorophyll content of rice at the late grain filling stage, with an average decrease of 31.3%, 19.9% and 30.7%, respectively. The effect on intercellular CO₂ concentration (C_i), electron transfer rate (ETR), water use efficiency (WUE) and other indexes were not significant in the two years, suggesting that elevated O₃ concentration induced reductions in A_sat was mainly due to the decrease in chlorophyll content, rather than the stomatal limitations of CO₂ transport. Warming significantly reduced the A_sat and g_s at the late grain filling stage of 2022, significantly reduced the C_i, and increased the WUE of leaves in the middle and late grain filling stage of 2021, but had no significant effect on other photosynthetic indexes and chlorophyll content. The open experimental conditions of O₃-T-FACE platform are greatly affected by the environment. Significant differences in the response of leaf photosynthetic rate to elevated O₃ concentration and warming across years at the late grain filling stage, as indicated by large photosynthetic loss in 2021. There was no significant difference in the effects of different warming ranges set in this experiment, suggesting that it is not enough to produce high temperature stress on the tested cultivar by increasing canopy temperature 1.5-2 ℃ under open conditions. No significant interactions were detected between elevated O₃ concentration and warming on leaf photosynthesis and chlorophyll content in this study, suggesting that high concentration of O₃ and air temperature will not induce synergistic or antagonistic effects on the photosynthesis of the tested rice cultivar.