Abstract: In modern engineering measurement, higher performance of illuminants is required to adapt the present engineering technical specifications for which have been demanded increasingly. An illuminant system with high extinction ratio and poly polarization was designed, based on the influence of the crystal birefringence and phase retardation on polarization state, as well as the relationship between the light refraction angle and the vibration direction, and a test program to verify the polarization state and extinction ratio of the emitting light in the system was designed. The illuminant system could easily output the polarized light including S polarization, P polarization and circular polarization by the computer-precisely-controlled stepping motor, and the system obtained the polarized light with high extinction ratio using the polarizing prism which was controlled by the translation and rotation device, and the extinction ratio of emitting light was no more than 510-6.