Combined dry and wet closed-loop cooling towers, the structure of which is divided into two parts: the upper part is a finned air cooler, and the lower part is a counter-current closed-loop cooling tower heat exchanger. The upper air cooler can meet the cooling process requirements in winter. In summer, a wet heat exchanger is used to take advantage of the latent heat of vaporization to lower the temperature of the heat medium, thereby reducing initial investment and maximizing water resource conservation.