Abstract: It is important to offer the kinetic energy equal to that of the natural rainfall in the rainfall simulation.This study analyzes the elements of the rainfall energy including the raindrop diameter,the raindrop impact velocity,and the uniformity of rainfall distribution,and then presents a method to realize the energy similarity by adjusting the rainfall intensity.Nevertheless,the raindrops from pressurised rainfall simulators could attain the terminal velocity over short fall distances less than 10 m if the pressure of the supplied water were high enough.