The asphalt nanopore in shale is the main occurrence space of shale gas.It is of great significance to identify the pore characteristics and formation mechanism of nanopore in shale reservoir for the study of shale gas reservoir formation and geological evaluation.By using focused ion beam electron microscopy technology, various pore types in black shale can be identified.A morphological classification scheme of pore types in black shale has been established for the first time in China.The formation process of nanopore in crude oil has been simulated by polarizing microscope and thermal simulatorand the dynamic process of nanopore formation has been reproducedand the nanopore has been identified.The mechanism of bubble forming suggests that nanopore existed in solidified asphaltene of shale is related to the gas production from crude oil pyrolysis.The residual asphalt is beneficial to the preservation of gas bubbles.The pore has ultra-low water saturation.The sphericity of the pore indicates the characteristics of high pressure and gas-rich, which is of great significance to the formation of over-pressure enrichment zone.