Abstract: By treated of different rank coal with chlorine dioxide, the change characteristics of surface properties of coal is studied by optical microscopic excrement and hydrophilic experiment. The result shows that the surface of coal is not smooth anymore, but appears etching cave, and new microfractures and roughness increases, connectivity enhances. Determine that the surface tension of chlorine dioxide solution is less than water at the same conditions, the contact angle of coal disposed by chlorine dioxide declined in different degrees, especially, the coking coal of Shaqu Mine could be changed from hydrophobic to one hydrophilic. Two experiments have a certain correlation, the result suggests that after surface modification of coal disposed by chlorine dioxide could promote gas permeation and transport to reduce temperature and dust.