A study was conducted to investigate the coupling effects of simultaneous heat and mass transfer through a membrane.A mathematic model was established to simulate the combined heat and mass transfer in the membrane separation process.With taking the membrane separation process of moist air as an example，the effects of temperature difference and moisture concentration difference on the heat and mass（moisture）transfer process were analyzed.It was found that the variations of the heat and mass transfer driving forces could cause the variations of both the thermal and moisture resistances of the membrane，which further affected the heat and mass transfer rates across the membrane，generating an additive effect.