To examine the effects of different levels of elevated CO₂ concentration and nitrogen fertilization on chlorophyll fluorescence characteristics of rice, a field experiment was conducted with automatic control system of CO₂ concentration in open-top-chamber (OTC). Using Japonica rice 9108 as the test material, the CO₂ concentration levels were set to control with ambient atmospheric CO₂ concentration (CK), CO₂ concentration increased by 160 μmol/mol over CK (C₁), and CO₂ concentration increased by 200 μmol/mol over CK (C₂); nitrogen fertilizer levels were set to low nitrogen (N₁:10 g/m²), middle nitrogen (N₂:20 g/m²), and high nitrogen (N₃:30 g/m²). The results showed that under low nitrogen condition, compared to CK, C₁ treatment increased F_o by 4.8% (P=0.031) at the jointing stage; C₂ treatment increased F_o by 6.3% (P=0.015) and F_v/F_m by 4.8% (P=0.003) at the jointing stage, as well as increased F_o by 12.7% (P=0.039) and F_v/F_o by 18.2% (P=0.039) at the booting stage. Under high nitrogen condition, compared with CK, C₂ treatment respectively decreased F_m, F_v and F_v/F_m by 3.6% (P=0.039), 4.9% (P=0.013), and 1.3% (P=0.039) during the filling stage. Compared with CK, the effects of C₁ and C₂ treatments were not obvious under the condition of middle nitrogen. During the whole growth period, the interaction effects of the elevated CO₂ concentration and nitrogen application on the chlorophyll fluorescence characteristics of rice did not reach a significant level. Our results suggest that the elevated CO₂ concentration increases photodamage to photosystem II of rice leaves and has certain inhibitory effects on its electron transfer capability, redox status of electron acceptor Q_A, maximum photochemical efficiency and potential activity. The negative effects can be effectively mitigated by proper nitrogen application.