Abstract: Phosphogypsum is a solid waste material. The storage of phosphogypsum wastes a lot of land resources and seriously pollutes the soil and water environment. And it may cause landslides. Therefore, it is extremely urgent to utilize phosphogypsum resources. In this paper we researched the cement-based stabilized phosphogypsum modified by sodium silicate to use in pavement base. Through unconfined compressive strength test, water stability test, dry shrinkage test and scanning electron microscope test, we obtained the physical and mechanical properties of cement-based stabilized phosphogypsum modified by sodium silicate using different dosage, incorporation mode and curing age. Sodium silicate promotes the hydration of cement and produces calcium silicate hydrate. It reveals the improvement mechanism of the strength of the mixture. The experimental results show that the compressive strength, water stability, water loss rate and dry shrinkage strain of cement-based stabilized phosphogypsum mixture can be effectively improved when the content of sodium silicate dissolved in water is 2%~4%. It is suggested that within 4-5 days after the construction of thepavement base, it is the best time to effectively control the water loss and dry shrinkage of the pavement base, so as to avoid the occurrence of cracks caused by rapid water loss.