Abstract: The 4238 working face fire in Panzhihua Huashan Coal Mine has adopted methods such as large-scale sealing of the whole No.4 mining area, gradually shrinking and sealing roadway associated with the fire area, liquid carbon dioxide pouring cooling and cooling in the fire area, and inorganic material filling were successively adopted, but the fire was not effectively controlled, with the passage of time, the fire gradually spread to the upper working face, and later developed into+1 030 level 4# fire zone. Aiming at this kind of extremely complex fire area, a partition isolation control technique is proposed. The fly ash compound colloid, which is formed by using fly ash as the main raw material and has obvious cooling, inerting and plugging effect, is used as grouting material, by constructing auxiliary control roadway, constructing grouting drilling to the main roadway that is related to the direction of return air to 4238 working face, injecting fly ash colloidal filling material through drilling holes, isolating 4238 working face fire area from 4236 side uphill and fire area periphery roadway and then governing each partition one by one, and CO in the 4238 working face and goaf disappeared, reaching the standard of unsealing and achieving staged fire-fighting effect. The results show that the fly ash composite colloid isolation technology can be used to deal with the large area of fire and the complex fire in the state of diffusion and spread quickly and efficiently.