Basic geological research of coalbed methane (CBM) in China, taking the reservoir formation as a key, has made significant progress in recent years. Macro-process and its geological controls of the CBM reservoir formation were discussed in the more basins and deeper level, which promoted the development of the classical CBM reservoir formation theories. Based on the original ideas, the essence of the CBM reservoir formation was studied in the light of the formation energy, some new academic viewpoints were suggested, and the particularity of the deep CBM reservoir formation was investigated. Geological conditions of CBM in China are complex and changeable and many basic geological problems need to be further resolved.