Abstract: Based on the review of previous study it is indicated in this paper that the coalbed gas reservoirs are the coal beds sealed by pressures and absorbed a large quantity of methane. They are principal and geologic units of coalbed gas accumulation and for exploring and exploiting. Coalbed gas reservoir-forming controls mainly include the factors of coal beds and pressure seal and conservation. The factors of coal beds provided crude matters for coalbed gas reservoirs. The pressure seal is essential ingredient for the coalbed gas reservoirs formation. Conservative conditions are the premise of coalbed gas reservoirs subsistence up to now.