Multi-medium reverse circulation drilling device and method for broken and soft coal seam

The invention discloses a broken soft coal seam multi-medium reverse circulation drilling device which comprises a double-wall drill rod, two ends of the double-wall drill rod are connected with a drill bit and a double-channel gas-water faucet respectively, an orifice of a drill hole is sealed by an orifice sealing piece, and the double-wall drill rod rotates through a driving piece; the main medium passage is arranged on the orifice sealing piece, the main medium passage is communicated with an outer annulus of the double-wall drill rod, and a main medium of the outer annulus is communicated with a central channel of the double-wall drill rod through the drill bit and a first communicating piece on the double-wall drill rod; the auxiliary medium passage is arranged on the double-channel gas and water faucet, the auxiliary medium passage is communicated with the inner annulus of the double-wall drill rod, and the auxiliary medium in the inner annulus is communicated with the outer annulus through a second co