As a new heat and mass transfer device，heat-source tower plays an important role in the heat-source tower heat pump system.Heat is absorbed from the ambient in winter and supplied to the evaporator of heat pump.There are some similarities and differences in heat and mass transfer between heat-source tower and cooling tower.Six primary differences are pointed out as follows：heat resistance，physical property of liquid，ratio of latent heat percentage，flow rate of circular water/liquid，effect of liquid float on the whole system，and direction and rate of heat transfer.Based on the similarities and differences of heat-source tower and cooling tower，the mathematical model of heat and mass transfer in the cross heat-source tower is proposed and the model is confirmed by experiments.Results show that the latent heat percentage of cross flow heat-source tower is less than 35% and the error of heat transfer rate between simulation and experiment is less than 10%.The model is accurate enough to simulate the heat transfer characteristic in the heat-source tower.