Abstract: To investigate the effect of elevated CO2 concentration and nitrogen fertilization on photosynthesis and growth of winter wheat, a field experiment was conducted to examine the variations of photosynthesis, biomass and yield structure of winter wheat based on the automatic control system of CO2 concentration with open top chambers (OTCs) using different CO2 concentrations and nitrogen fertilization rates. Three levels of CO2 concentration, i.e., ambient CO2 concentration (CK), CK 40 μmol/mol CO2 (T1), and CK 200 μmol/mol CO2 (T2) and three levels of nitrogen fertilization, i.e., no nitrogen input (N0, 0 kgN/hm2), medium nitrogen input (N1, 220 kgN/hm2), and high nitrogen input (N2, 400 kgN/hm2), were applied in this study. The results showed that under the low level of light intensity (PAR ≤ 200 μmol/(m2·s)) and CO2 concentration (Ci ≤ 300 μmol/mol), the net photosynthetic rate (Pn) increased linearly followed by a leveling off. Compared with CK, Pn was increased by 19.93% under T2 treatment (P=0.013), while no significant differences were found in the maximum net photosynthetic rate (Pnmax), dark respiration rate (Rday), or photorespiration rate (Rp) under CK, T1 and T2 treatments. From the jointing to the flowering stages, the plant height, dry weight of leaf and stem sheath were significantly increased under N1 and N2 treatments compared with N0 with different CO2 concentrations. From the heading to the flowering stages, the dry weight of stem sheath was significantly increased by 37.4% (P=0.035) under T2N1 compared with CKN1. In comparison to T1N0 treatment, the grain number was significantly increased by 29.69% (P=0.006) and 42.27% (P=0.001), respectively, under T1N1 and T1N2 treatments. Compared with T2N0 treatment, the grain number was significantly increased by 16.66% (P=0.011) and 19.19% (P=0.005), respectively, under T2N1 and T2N2 treatments. For the 1000-grain weight, it was significantly increased by 7.79% (P=0.004) and 6.23% (P=0.015), respectively, under T2N1 and T2N2 treatments as compared to T2N0 treatment. Compared with CKN2 treatment, the economic coefficient was significantly increased by 3.70% (P=0.025) under T1N2 treatment. Our study showed that the elevated CO2 concentration significantly increased Pn of the light response curve of winter-wheat. Elevated CO2 concentration and nitrogen fertilization stimulated the accumulation of dry matter in winter-wheat, with the latter having greater stimulation on the accumulation of dry matter during the early growth stage of crop. Elevated CO2 concentration and nitrogen fertilization affected the yield structure of winter-wheat by increasing grain number and 1000-grain weight, with T1N2 treatment showing the greatest impact on grain number.