Abstract: Effects of long-term elevated CO2 on net CO2 uptake，growth and flowering of Phalaenopsis‘Neishan Guniang’were studied under elevated CO2（800 ± 50）μmol ? mol-1 and ambient CO2 concentration（approximately 400 μmol ? mol-1）for 240 d. The results showed that Phalaenopsis was a CAM orchid with the net CO2 uptake rate and the contents of titratable acidity reached the maximum at 22：00 and 6：00，respectively. Elevated CO2 significantly increased the net CO2 uptake rate in Phalaenopsis leaves，which was almost arrived two-fold comparison of in the control，and the content of titratable acidity was increased 44% by CO2 elevated. Elevated CO2 resulted in the increase of the accumulation of biomass which increased by 31% in dry weight and 28% in fresh weight. In addition，elevated CO2 not only advanced the flowering time by 5.4 d in Phalaenopsis，but also increased flower quantity and quality，with the number of flowers increased by 66%.

Key words: Phalaenopsis, CO2 elevated, CO2 uptake, growth, flowering