Abstract: The application of hydraulic fracturing technology in a certain block of offshore oil fields lacks of fracturing mechanism analysis and development laws evaluation. A low-permeability fracturing fracture initiation model was established by analyzing the principles of hydraulic fracturing. A true triaxial hydraulic fracturing test device was used to conduct vertical well hydraulic fracturing simulation tests, and on-site application was carried out in offshore Block A to evaluate the fracturing effect. The results show that the higher the fluid viscosity, the smaller the fracture initiation displacement. The fracture initiation displacement is linearly positively correlated with the formation fracture pressure gradient. The deeper the perforation depth and the smaller the perforation angle, the higher the fracture initiation displacement. The optimal fracturing effect is achieved when the single spiral (45°) perforation method with a hole density of 16 holes/m, the injected fluid viscosity of 30～40 mPa∙s, and the injection flow rate of 2.7 m3/min are used in the fracturing process parameters. Four fracturing wells in Block A achieved 23% increase in average oil production per well per day. This study provides theoretical support for the application of hydraulic fracturing technology in offshore oilfield blocks.