The effects of CO2 enrichment on growth of maize (Zea mays L.) were examined. Parameters analyzed include growth characteristics, yields, photosynthetic rates, evaporation rates and photosynthesis-related characteristics under elevated CO2 . The plants were grown in growth chambers with a 12-h photoperiod and a day/night temperature of 28/21~circC at the seedling stage and 30/23~circC from the silking stage. The plants were exposed to two elevated CO2 of 500, 700ppm and ambient levels (350 ppm). Chalok 1 and GCB 70 germinated three days after seeding, and germination rates were faster in the elevated CO2 than the control. Germination rates displayed significant differences among the CO2 treatments. At the seedling stage, leaf area, top dry weight, and photosynthetic rates, and plant height indicated positive relationship with elevated CO2 concentrations. At the 5~6 leaf stage, CO2 concentration also indicated positive relationship with plant height, leaf area, top dry weight, and photosynthetic rates. At the silking stage, increased plant height of Chalok 1 was noted in the CO2 treatments compared to the control. No significant differences were noted for GCB 70, in which leaf area decreased but photosynthetic rates increased progressively with CO2 concentration. Stomatal aperture was a little bigger in the elevated CO2 than the control. CO2 concentration was negatively related to stomatal conductance and transpiration rates, resulting in high water use efficiency.