Abstract: In this paper, regarding the design scheme of the main-auxiliary combined cooling tower for 660 MW power plant units, a 3-D simulation model is built to study the impacts of ambient wind on the flow fields both inside and outside of the cooling tower. Also this paper explores how the variations of main and auxiliary circulating water temperature drop are affected by the ambient wind direction, the type of the heat exchanger of the auxiliary cooling unit and the method of increasing the number of cooling triangles. The results show that the ambient wind direction has very limited effects on the main circulating water temperature drop (about 1 °C) but significant impacts on the auxiliary circulating water temperature drop (about 5.8 °C). If the four-row-tube arrangement is adopted in the heat exchanger, the drop of the auxiliary circulating water temperature increases by about 0.2 °C, and the drop of the main circulating water temperature decreases by about 0.06 °C. The research results can provide reference for the engineering implementation of the design scheme of the main-auxiliary combined tower.