The invention discloses a method for extracting high-pressure hydraulic cave-manufacturing gas from a rock roadway crossing hole and belongs to the field of a soft high outburst seam gas extracting method. The method is characterized in that upward or downward large-diameter crossing holes are constructed into the coal seam roof or the coal seam floor by drilling and stamping integration equipment in the rock roadway of the soft high outburst seam; the cave is manufactured hydraulically by combining hydraulic fracturing with hydraulic jetting punching; a great cave is established in the coal seam and a fracture expansion region is formed around the cave, so that the coal ground stress is reduced, the bare area of the coal seam is increased, and the permeability of the coal seam, the gas extracting efficiency and the gas extracting quantity are improved. The method has the advantages that the large cave is established in the soft high outburst seam and a huge fracture expansion mesh is formed around the cave, so that the coal ground stress is reduced, the bare area of the coal seam is increased, and the permeability of the coal seam is improved; besides wide space is provided to convey and extract the gas, the gas extracting efficiency and gas extracting quality in the soft high outburst seam can be effectively improved, and a new way to treat the gas in the soft high outburst seam is provided.