The influence of temperature on the garnet-type polarization modulation was investigated. The garnet-type polarization modulation was prepared by magnetron sputtering method, the polarization properties and optical spots of laserbeam through garent and garnet-type polarization modulation were examined by Stokes polarimeter and CCD. The experimental results show that the Stokes parameters of the laser beam passing through different materials present different trends, while the degree of polarization, degree of linear polarization and degree of circular polarization are nearly unchanged as the ellipticity angle does not change, when changing the temperature from 25 to 75 °C.