In this paper, the behavior of grouting cement mortar to reinforce highway subgrade is analyzed from the aspects of stability, fluidity, viscosity, bleeding ratio and setting time of cement mortar. Mixing a certain content of fly ash to cement mortar can improve stability of mortar. Mixing water glass can improve stability and increase forming stone percent of mortar and can reduce the fluidity of mortar. While mixing CaCl 2 can increase fluidity of mortar also.