Abstract: Taking M medium?rank coalbed methane (CBM) field of Bowen basin in Australia as an example, this paper proposed corresponding approaches for development of the medium?rank CBM by SIS (surface into seam) horizontal wells, based on the well group model developed by the reservoirs with four types of petrophysical properties classified by permeability and CBM content. For Type I and Type II reservoirs with high permeability and high gas content, the approach is to optimize the well controlled area, design the horizontal wells thatare perpendicular to cleat and put infill wells in the late stage of production, by which the drilling footage and well number can be greatly decreased. For Type III reservoir with medium permeability and high gas content, the approach is to properly increase the well controlled area and optimize the branch length and angle of SIS wells by considering the influence of early production wells on the regional pressure in this area. For Type IV reservoir with low permeability and high gas content, the development effects by SIS well and multi?branch horizontal well are poor or uneconomical, due to the well controlled area is smaller, suggesting not to develop it at present