Closed wet cooling tower (CWCT) is an indirect-contact evaporative cooler, in which ambient air, spray water, and process water function together. In order to improve its thermal performance, a new heat transfer strategy is proposed. The influence of fan frequency, spray density, and processing water flow on the thermal performance of CWCT is obtained by combining theoretical and experimental research. By fitting the experimental data, the empirical formula of heat and mass transfer coefficient is obtained. The research results can be used to improve the cooling efficiency and enhance the heat and mass transfer of CWCT.