Abstract: The influence of different arrangements on the external flow field of the sunken cooling tower by MRF (multiple reference system mode) is simulated. The results show that with the increasing of the sinking depth, the distance between the inlets of cooling tower will decrease, same is the distance between the cooling tower inlet and the pouring pit; then the hot plume of cooling tower is impacted easily by the ambient wind speed and the inlet negative pressure of cooling tower, and the recirculation rate will be higher. Meanwhile, the important factors that influence the recirculation rate in the order from big to small are the sinking depth, the distance between the cooling towers' inlets and the distance between the inlet and the pouring pit. Considering the civil construction cost and motor noise, it is suggested that the sinking size of the pit should be reduced and the sinking depth be increased properly. Two recirculation rate improvement schemes are proposed: the installation of 70 cm reducing pipe and that of 70 cm straight pipe with muffling functions on the air-duct. Simulation results indicate that the effect of the reducing pipe is better than that of the straight pipe for cooling tower's hot plume.