Based on enrichment characteristics and formation theory about low rank coal bed methane (LCBM ) at home and abroad ,national LCBM genetic types and formation models have been studied .The results show that genetic types of LCBM include thermogenic methane ,biogenic methane and mixed methane .The characteristics of low rank coal reservoir include shallow bury ,low contents ,large thickness , high permeability and transformed easily ,coexisting with other oil gas .Based on the previous research results of formation models dividing through lithology ,structure conditions ,locations and hydrogeololgy conditions ,synthesize dynamic formation model has been proposed in this paper ,including material base of favorable sedimental environment ,migration pressure difference of constructs ,methane supply and preserve of hydrogeololgy conditions ,discussing new thought of selecting area of LCBM .Taking Yilan coal-bearing basin for an example ,combined previous research results and geological conditions ,reservoir forming and accumulation model of LCBM in China is proposed ,which is advantage coal faces rich water area accumulation model in slope with coupling between primary and secondary origin .%基于国内外低煤阶煤层气的富集特点和成藏理论的追踪，对我国低煤阶煤层气的成因类型和成藏模式展开了研究。结果表明，我国低煤阶煤层气藏成因类型有热成因、生物成因和混合成因；煤储层特征包括埋藏浅、含气量低、厚度大、渗透率高且易改造及与其它油气共生等特点；前人从岩性、构造条件及煤储层所处位置、水文地质条件等对低煤阶煤层气的成藏模式进行了划分。基于以上研究，认为应以动态的观点来认识和探讨以有利成煤相带为煤层气富集的物质基础、以构造体为煤层气运移压差和以水动力条件为气源补给和封盖的条件的低煤阶煤层气成藏模式。以东北依兰盆地为例，结合我国低煤阶煤层气盆地的地质特征和前人研究成果，建立了我国低煤阶煤层气的成藏富集模式，即原生成因和次生成因叠合下的斜坡区成煤优势相带高富水区的煤层气富集模式。
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