CH4 isothermal adsorption curves of 83 coal samples were systematically analyzed，and the statistical model between coal rank and parameters related to adsorption-desorption characteristics were established to reveal the influence of coal rank on CBM adsorption-desorption characteristics in the western Guizhou-eastern Yunnan region. Also，its implications on the optimization of production-layer combination were discussed. The analysis shows that a higher coal rank leads to denser coal，much larger specific surface areas of micropores，and further better adsorption to CH4，resulting in higher desorption pressure at key nodes（starting，turning，and sensitive points）and greater overburden pressure differences at every desorption stage（inefficient，slow，fast，and sensitive stages）. When vitrinite reflectance is more than 3.0%，the pore-fracture system and CBM adsorption-desorption characteristic parameters of coal tend to be stable. This differential distribution of coal rank in the study area and the spatial differentiation of the superimposed pressure system further complicate the desorption of different coalbeds. The high desorption efficiency of each production layer before coalbed exposure is an important prerequisite to ensuring the commingled production and gas productivity of each layer. Based on this，the seven constraints on the feasibility of the production-layer combination are identified to guide the future project design of commingled production.