To investigate the best application concentration of CO2 in tomato planting,an experiment was conducted to explore the effects of CO2 concentrations on the growth and nutrient utilization of tomato by applying different concentrations of CO2 (300,600,800,1 000,1 200,1 400 μL/L) and chemical fertilizer (no fertilization,a 20% reduction of normal fertilization,normal fertilization and a 20% addition of normal fertilization) together.The results showed that,when the CO2 concentration was 800 μL/L,the yield of tomato increased by 9.11%~67.76%,vitamin C content in tomato increased by 12.52%~38.60%,soluble sugar content in tomato increased by 45.77%~85.92%,nitrate content in tomato decreased by 7.78%~38.18%,and the tomato yields under the no fertilization treatment and the 20% reduction of normal fertilization treatment were higher than those under the normal fertilization treatment and the 20% addition of normal treatment.Therefore,the application of CO2 (800 μL/L) showed significant effect on increasing tomato yield whilst reducing chemical fertilizer application,and improving the quality and accumulation of N,P,K nutrient of tomato.