Abstract: According to the exploration,confirming that the coal measure mud shale of late Permian Longtan Formation in Junlian Coalfield had certain gas- bearing,an d an evaluation was conducted on the gas resources potential of shale reservoir. Several means were applied to the related tests on hydrocarbon generation condition,rese rvoir physical property,gas- bearing property and other aspects of mud shale samples from the roof and floor of seam in late Permian Longtan Formation of Junlian Coalfiel d. The results showed that the kerogen type of shale in Junlian Coalfield was type I ,in postmature and thermal evolution stage,vitrinite reflectance was 3. 11% in average, total organic carbon was 2.66% in average,a clay mineral content was 54% in average,a quartz content was 39.5% in average and a desorption gas content was 1. 9 m3/ t in average. The analysis showed that each index of the shale reservoir in Longtan Formation of Junlian Coalfield basically reached at minimum requirements of shale gas development. But in comparison with US Barnett shale,except for the shallow depth,each index was relatively poor. Especially the quartz content and other fragility mineral content were low and were not favorable to the crack fracturing of shale reservoir.