The dissolved CO 2 accumulation has become an important factor restricting production in the high-density recirculating aquaculture system in which pure oxygen injection is used. In this paper, a novel CO 2 removal device is designed for the recirculating aquaculture water environment based on the principle of gas exchange. In terms of experiments, the DOE (design of experiment) method is applied to design three factor two level orthogonal experiment, Further, significance effect of gas to liquid ratios (G / L), inlet CO 2 concentration, the water flow rate (Q W ) on CO 2 removal efficiency is analyzed. Results show that G/L has the most significant influence on the CO 2 removal efficiency. Influences of the latter two on CO 2 removal efficiency are not apparent. Tests results of G/L effect on CO 2 removal efficiency show that, when G/L=1∼5, CO 2 removal efficiency increases rapidly with the increase of G/L; when G/L=5, CO 2 removal efficiency=80%∼88%; when G/L=8, CO 2 removal efficiency=86%∼92%, when G/L>8, CO 2 removal efficiency increases gently with the increase of G/L. Considering both system energy saving and effective removal of carbon dioxide, G/L=5∼8 is considered to be the best for the aquaculture water CO2 removal device running, CO 2 removal efficiency=80%∼92%.