Abstract: In order to analyze shale gas reservoir forming conditions of lower silurian series from longmaxi formation in northwestern of Hunan province and find fa vorable areas, the authors tested the features of shale gas from the following aspects, the organic geochemical characteristics, the pore-fracture developing features.T he results showed that the average thickness of the shale of lower silurian series longmaxi formation was 24 meters and the content of total organic carbon (TOC) was between 0.7% ~ 1.5% overall.The kerogen type was I type and the vitrinite reflectance (Ro) was 1.06% ~3.95% and the average value was 1.99%, which indicated the shale gas was at the stages of mature and post mature.The pore-fracture system was well developed and the average porosity was 5.6%.Overall, the black shale of low er silurian series longmaxi formation in northwestern Hunan Province had ideal exploration and development conditions and the favorable area was located in Zhangjaiji e- Sangzhi- _Yongshun district.