From the analyzing of the process of production at CBM wells on the basis of hydro geologic, this paper elaborates the mechanism of water drainage and gas production at CBM wells.

• 从水文地质的角度分析了稳定状态和非稳定状态下煤层气井的生产过程,揭示了煤层气井生产的实质就是通过排水达到降压、采气,以地下水运移规律为指导进行排采是煤层气井持续、稳定、高产的关键。