Abstract: The solution process of falling film wetting rate was established based on minimum energy model. The approximate solutions of minimum wetting rate, minimum film thickness and film velocity distribution were obtained using Ritz method. Only the variables involved sinusoidal function were analyzed, while the cosine volume approximately equal to one, which made the film velocity distribution convert to single direction variable function, and reduced the redundant steps of the solution process with ensuring accuracy. This method provides a great convenience for the falling film wetting rate and the corresponding minimum thickness.