As there are numerous coalbed methane (CBM) wells with low or zero gas production after traditional hydraulic fracturing in China, new technologies are needed for both the secondary stimulation of these wells and new wells' stimulation. Based on the results of laboratory tests and theoretical analysis, this paper, the first of a two-part series, demonstrates the theory of a new combined stimulation technology for CBM wells. Firstly, gas contents in the coal seam, neighbouring shale and sandstone were measured and calculated. Then, the geomechanic, mineral composition and permeability of the tight sandstone were tested. Based on these tests and calculations, a combined stimulation technology is demonstrated. This new technology is to expand gas production from coal seams to coal measures; to expand the stimulation object from unitary coal seams to coal measures; and to change the stimulation method from the conventional hydraulic fracturing to fracture network stimulation. Results show that: (1) in addition to CBM, significant amounts of shale gas and tight sandstone gas can serve as complements of CBM; (2) the highest fracability formation is tight sandstone, followed by mudstone and coal. It is concluded that this combined stimulation technology can be demonstrated as conducting combined fracture network stimulation for coal measure gas reservoirs through multilayer and multi-cluster perforation, quadruplex hydraulic fracturing and other auxiliary technologies, e.g., ball-injection temporary plugging and limited entry fracturing. In part 2, the application of this combined stimulation technology to a CBM well in the Sunan Syncline is described.