China has a large amount of low-rank coalbed methane resource, coalbed methane resource existed in low rank coal below medium volatile over 15.13 trillion cubic meter. Till now, there is still no successful production, Studies on geology should be strengthened. In this paper, the authors analysized the coalbed methane forming conditions and characteristics in Tuha basin, geological settings and coal accumulation, coal series characteristics, biogenic gas preservation had also been considered. In the end, coalbed methane reservoir type and distribution patterns had been determined. Tuha coalbed methane reservoir could be divided into three types, including basin depression reservoir, basin margin steep and mild slope reservoir. In terms of matching feature characteristics of reservoir forming, two typical type can be discriminated, including reservoir forming- dissipation type and forming-migration-dissipation type. This will be an important acknowledge for low rank coalbed methane genesis and exploring.