Abstract: During the normal mining process, the working face is vulnerable to the harmful gas intrusion from high temperature fire area of surface slag table because of its fracture in the overlying surface of the fully mechanized caving face with close distance high temperature loose media of the south S01 fully mechanized caving face of Heidaigou Coal Mine, which will cause the spontaneous combustion of the residual coal in the goaf. Based on the theoretical basis of fire prevention of traditional precautionary grouting, the dynamic properties and wettability of the slurry can be improved by changing the liquid solid contact angle and surface tension. In the process of experiment, the composite slurry with the anti-fire effect of the best foaming and wettability is found. The practice show that the improved composite slurry has a prominent grouting effect on the key area of the overlying surface slag table in the working face, which can ensure the safe production of the working face.