In order to investigate the heat transfer process in the closed-type heat source tower under the non-frosting condition in winter, the finite difference method was adopted to develop the dynamic heat and mass transfer model. Comparing the calculated results with the experimental findings, the root mean square error of the outlet solution temperature turns out to be 0.201℃ and the validity of the model is verified. The dynamic heat transfer characteristics of the closed-type heat source tower on variable load operation are analyzed through experiments and simulations, which show that the closed-type heat source tower, as a heat extraction device, can provide a relatively stable heat source for the evaporator when the heat pump unit working under changing operating mode. Besides, compared with the traditional air source heat pump, the closed-type heat source tower has lower frost formation risk and higher energy saving potential under low temperature and high humidity environment.