The deformation failure of drift at a shorter distance from extraction was mainly dependent on the magnitude of dynamic support pressure, acting on the host rock of drift, at the spacing extraction face by the action of mining disturbance, while this magnitude scale was dependent on the propagation law and range of advanced dynamic support pressure in the coal seam floor. In the case drift at Liuwan coal mine, an observation upon support pressure and drift deformation was taken, and their law of dynamic change was found through the medium of analyzing about ten thousand measured data. Based on this law, the corresponding maintenance of drift was done, with good results.