In view of the problem that the sealing effect of goaf is not ideal in coal mining, the performance requirements of the sealing wall were discussed, and in detail the advantages and disadvantages of the commonly used sealing materials and sealing forms were analyzed. On this basis, the principle of flexible sealing to adapt to roof deformation was put forward, and the construction technology of closed wall filled with super high water material was developed. The application in the 1127 working face of Xingdong Mine showed that the technology was simple. Three months after the completion of construction, the sealed wall was in good condition without cracks on the surface, and the CO concentration in the sealed wall was zero. The ideal sealed effect was obtained, which can be used for reference for the sealing of goaf in spontaneous combustion and high gas mines, with a broad application prospect.