A magneto-optical-modulating-double-frequency system is set up and actualized with temperature controlled added. The eigen rotation and Verdet constant of the paramagnetic terbium glass Tb20 are measured in 293K～343K. With the temperature goes higher,the eigen rotation increases to a stable value gradually and the Verdet constant decreases keeping to the theoretical formula. The experimental results show that the terbium glass has sensitive temperature response. When it is used,especially used as Zero-Lock gyro Faraday bias element,temperature compensation must be taken,and several potential approaches to temperature compensation are also given.