Abstract: The plant height, stem diameter, leaf area, specific leaf mass, chlorophyll content and yield components of soybean under ambient and elevated CO2 levels were measured, and their responses to elevated CO2 were analyzed. The results showed that plant height increased by 15.74% and 21.57% under elevated (550 and 750μmol/mol)CO2, compared to the ambient air CO2 concentration. The stem diameter increased by 8.62% and 13.79%. At the same time, the leaf area increased by 7.27% and 14.08% with air CO2 enrichment at grain filling stage. The pod Number per plant increased 6.87% and 11.61%, and seed weight per pot increased 15.19% and 29.10% in two high CO2 levels.