This disclosure provides calculation methods for the reflectivity of normal incident wave on the interface, the absolute reflection critical angle of the wave, the relative reflection critical angle of the wave, and the refraction-reflection symmetrical angle of the wave. These calculation methods can calculate the reflected wave energy on interface, the angle at which the incident wave would all be reflected on the interface and wave energy would be trapped, the angle at which the incident wave begins to be reflected, and the angle at which the reflected wave energy equals the refracted wave energy. The provided calculation methods could be widely used in various fields such as light, electromagnetic waves, sound waves and etc.