The invention discloses an expansion-hose hydraulic fracturing method for coal seam permeability increasing. The expansion-hose hydraulic fracturing method for coal seam permeability increasing comprises the five steps of assembling a hydraulic fracturing system, drilling a coal seam, arranging expansion hoses, fracturing and carrying out pressure relief. According to the expansion-hose hydraulicfracturing method for coal seam permeability increasing, the expansion hoses in hydraulic fracturing drilled holes are expanded through high-pressure water provided by a high-pressure pump, fracture structures of the coal seam are damaged under the action of the expansion hoses to form cracks, so that the effects of permeability increasing and pressure relief are achieved; and the method avoids aphenomenon that water blocks air holes, in general hydraulic fracturing methods simultaneously, avoids waste for water resources, and solves the problem of difficult gas extraction for a soft coal seam with low permeability and high gas concentration at present.