Abstract: It is found that water glass can not only form gel itself in high temperature and produce abundant sediments with the interaction of high salinity formation water, which can control injection profile through better plugging; but also form substance with high viscosity, increase water viscosity and decrease mobility ratio between oil and water. With the interaction with active components of crude oil, water glass can produce surface- active substance, which can lower interfacial tension of oil and water and has good oil displacement efficiency. The results from drilling core physical simulation show that water glass can easily leak into formation and has preferable profile control and oil displacement ability under high temperature and high salinity.