Aim\ To study the propagation process of light under normal incidence in a system of two layer uniaxial birefringence. Methods \ There are two reflected beams and two refracted beams on the interface of the system for each incident beam. The propagation process is shown exactly in matrixes. Results and Conclusion\ The number of beams is increasing in geometric series when the light propagates in the two layer system

and it is necessary for study of the interference pattern of the system and for further development of Fabry Perot interferometer.