Abstract: Physical property is bad in low permeability reservoir, and commercial oil flow can't be obtained without acid fracture process. Log interpretation is difficult for productive reservoirs. Based on reservoir characteristics of Leng 46 block in Liaohe Oilfield, a set of method studied on net pay thickness standard was established. In order to detect dividing precision of net thickness, 5 wells in coring wells were selected to compare with core thickness and log thickness. Dividing precision ratio is 100%. The net thickness of single well had been determined in 39 wells, and it ensured success of layer perforation effectively and provided reliable evidence for waterflood development.