In-situ modified mining technology is one of the major directions of future mining technology development. In this paper, we combined coal supercritical water treatment technology and in-situ modified mining technology to study the percolation and deformation characteristics of anthracite coal of Φ25mm×50mm in the Sihe Mine under triaxial stress supercritical water environment. The results show that under the subcritical and supercritical water injection conditions of 365℃, 400℃ and 435℃, the permeability of anthracite coal decreases by 56.75%, 96.93% and 94.99%, respectively, compared with the original coal, and the overall permeability changes in the trend of rapid decrease and then slightly increase; the percolation channels of anthracite coal in the early stage of the experiment will gradually close, and after a period of continuous heat injection, the percolation phenomenon will The recovery time is about 43.5h, 24.54h and 19.81h; the recovery is accompanied by a sharp axial compression deformation, and the higher the test temperature is, the larger the axial compression deformation is, about 0.06, 0.11 and 0.16.