Preventing snow buildup on an inclined roof using a falling water film is studied in this paper. A cluster of physical models for a gas-water-snow system has been developed and solved with a fully implicit control-volume finite-difference procedure. The contact flow pattern of a turbulent water film and a laminar gas stream was used in the simulation. The temperatures of the ambient saturated atmosphere and the falling snow were assumed to be equal and below zero Celsius. The outlet temperature of the water film was set at zero Celsius for the critical state. The effects of various parameters on heat transfer and water film temperature drop were investigated. The results revealed that it is feasible to use a falling water film to prevent snow buildup on an inclined roof. It was clarified numerically that among the factors influencing water film temperature drop, the snowfall intensity, the water film flow rate, the roof length and inclination play important roles. Of course the ambient temperature and wind speed also contribute to the water film temperature drop. The critical states of the inlet temperature and flow rate of the water film for various parameters were calculated in the present paper. The intensive heat transfer occurs in a very thin layer near the free surface of the water film in response to snow melting at the gas-water interface. The numerical results were correlated in terms of effective Nusselt number, and Reynolds number, Prandtl number and Gukhman number for simplified predicting. The maximum deviation of the numerical data from the regression line is approximately 15.6%, which causes an uncertainty of less than 3% in simple prediction.