Abstract: Pearl River Mouth Basin is a major area for the accumulation of low-permeability oil and gas reservoirs with huge resources in the offshore China. L44 Oilfield in Lufeng Sag is the first integral low-permeability oilfield that have been fractured and developed in the eastern South China Sea. However, problems such as insufficient scale of reservoir reconstruction and unclear understanding of fracture initiation mechanism occur after fracturing. Based on seismic interpretation, logging and geological data, a geology and engineering integrated modeling method for offshore low-permeability oilfield has been established, which enables to more accurately predict fracture propagation. In addition,3D geomechanical modeling has been conducted and geological/engineering double sweet spots have optimally been selected in the study area.The upper limit of reservoir perforation interval applicable for offshore low-permeability oilfield has been proposed in fracturing design, and the new fracturing scheme design and capacity simulation have been conducted for Well C3, showing a basically consistent production level with the expectation after the secondary fracturing. The study results show that: (1) Given a low displacement, when the length of perforation interval increases from 4 m to 16 m, the fracture length in a stage decreases by 30 m on an average, and the cumulative production capacity of a single well decreases by 88% in the first five years; (2) An increase in the length of perforation interval inhibits the scale of reservoir reconstruction. When the perforation interval is more than 6 m, the scope of reservoir reconstruction greatly decreases; When the perforation interval is less than 6 m, the scope of reservoir reconstruction insignificantly decreases; As a result, the optimal length of perforation interval should be no more than 6 m; (3) Given a perforation interval of less than 6 m, the average reservoir reconstruction volume increases by 10.97% when the construction displacement increases by 1 m³/min. A higher construction displacement enables to further increase the reservoir reconstruction volume. The geology and engineering integrated modeling method for offshore low-permeability oil fields provides a new idea for the development plan and fracturing scheme design of low-permeability oilfields in the eastern South China Sea, which is beneficial for improving development benefits of oilfields.