Pore space is characteristic in Lower Silurian Longmaxi shale reservoirs in southeastern Chongqing and northwestern Guizhou areas.Shale samples are collected from Wells YY-1,XY-1 and TY-1 in the areas.Observed with SEM,four types of pores can be recognized,including intergranular pores,intragranular pores,organic-matter pores and microfractures,most of which are macropores (>50nm) and mesopores (2~50nm).Mineral intercrystalline pores are common in intergranular pores.Mineral aggregates,such as pyrite framboids,are general in intragranular pores.Organic-matter pores are mostly round or elliptic with large sizes as macropores and/or mesopores.By the micro-CT scanning to part of samples,the 3-D structure models of nanometer-scaled pores are re-established.It is shown that most micropores are isolated or stripped with poor pore networks and connectivity in Longmaxi shales.