Abstract: On the basis of the Fermat principle of the anisotropic medium, the reflection of the incident e-ray is discussed and analyzed on the internal boundary surface of the uniaxial crystal. The reflection formulas of both o-ray and e-ray reflected is derived in any direction of optical axis of the uniaxial crystal, and some special cases are discussed. It is also pointed out that the result is the same as those calculated on basis on the boundary condition of the electromagnetic wave.

Key words: uniaxial crystal, Fermat principle, wave normal, internal boundary