Abstract: Proceeding from the propagating Jones matrix of laser, the relation between the eigenpolarization and the temperature in the four-frequency differential laser gyro was obtained in combination with the empirical formula of quartz crystal rotatory power versus temperature and the method of calculating eigenvectors, for the research on the influence of the quartz crystal temperature effect on the four-frequency differential laser gyro. The variation curves of the light ellipticity and the differential loss with the temperature were acquired by the numerical analysis. The result shows that the influence of quartz crystal temperature effect on the optical polarization characteristics is closely related to the amplitude reflectivity and the phase shift of the mirror. For typical gyro parameters, the differential loss and the ellipticity increase respectively from 0 to 10-6 and from 0.122 to 0.138 when the quartz crystal temperature is in the range of -60℃ to 60℃.