Abstract: The main body of Chang-6 reservoir in Huaqing region is delta deposition,with the lithology being mainly the fine sand stone.Four-property relation of target section in the region were studied by thin section,mercury penetration,logging,showing that①Chang-6 reservoir in the region belongs to typical low-porosity and low-permeanbility oil interval,②diversity between lithology and physical property controls the enrichment of the reservoir,and ③cut-off properties standard are thus determined with a porosity of 8% and a permeanbiliy of 0.08×10^-3μm²,and ③the lower limit of electrical property is determined to be 16Ω·m and the acoustic time to be 215μs/m.