Closed-loop cooling towers with both dry and wet systems, divided into two parts structurally: the upper section is a finned air cooler, and the lower section is a counter-current closed-loop cooling tower heat exchanger. The upper air cooler can meet the cooling process requirements during winter. In summer, a wet heat exchanger is used, utilizing latent heat of vaporization to lower the temperature of the heat medium, which not only reduces the initial investment but also maximizes water conservation.