Abstract: Delta sediments are the main deposits in the Chang 6 oil beds of Yanchang Formation in Fuxian area of the Ordos Basin and the sand bodies of distributary channel and subaquatic distributary channels are main reservoirs for the hydrocarbon.Fine lithic arkose sandstone and fine arkose sandstone are main sandstones of the Chang 6 reservoir.They have line and point-line contact forms with pore and thin film cementation between rock grains.The Chang 6 reservoir is characterized by the low component maturity and high textural maturity.The main pore types are granular pore and secondary feldspar-dissolution pore which are mainly composed of small hole and micropore.The Chang 6 reservoir has super low permeability and is accessed densify reservoir of which the permeability is less than 3×10^-3μm².The strong compaction and cementation are the main factors which cause the low porosity and low permeability of the reservoir,while dissolution is the main factor for improving the physical property of the reservoir.