Based on the research of the black shale in the Ordovician - Silurian in the Upper middle yangzi region (the Sichuan basin and the peripheral),especially through the observation on the samples by microscope,the Argon ion polishing scanning electron microscopy and FIB,the development characteristics between the lower part of upper siliceous shale and the upper part of the black silty shale is distinguished.Combinated the research of the sequence stratigraphy and sedimentary facies,the black shale from the bottom to the top reflect a change from the deep shelf to the shallow shelf.The black siliceous and carbonaceous shale has a large quality of bioclastic,organic matter and organic pore.And the black silty shale has a large quality of terrigenous clastic mineral grains and inorganic pore,lower organic matter.