Abstract: In an agitated reactor with hydrofoil impeller, effects of draft tube structure and solid content on power consumption and gas holdup were investigated. Single impeller was used when the liquid height to tank diameter ratio was 1.0. With the aid of draft tube, the power consumption decreased while the gas holdup increased. The optimal holes area ratio of draft tube was 16.4%. Lower power consumption and higher gas holdup were obtained when the hydrofoil impeller was upward. Power consumption increased with the increasing of solid content. The gas holdup in gas-liquid system was found to be much greater than that in the gas-liquid-solid system. The correlation formula of gas holdup was obtained when the holes area ratio of draft tube was 16.4% and the hydrofoil impeller was upward. Furthermore doublecombined impellers were installed when the liquid height to tank diameter ratio was 1.5 and the similar conclusions as single impeller were obtained.