Abstract: Based on the stress optics law and the theory of elasticity thermal stress, the relation between optic path difference of double refraction and main stress difference is derived. The effect of the stress on the imaging quality of optic colophony lens was examined in changing temperature environment with a photoelasticimeter. At 28℃～68℃, the isochromatic line of optic colophony lens of thermal stress was determined, and the interference fringe patterns were obtained at different temperatures and main stress differences. It is concluded that the thermal stress produced by temperature change does not converge, and no residual stress exists when temperature recovers. The image quality of the optic lens is not affected in 40℃ temperature variation range.