Wellbore integrity management is one of the key issues to ensure the safe production of oil and gas wells. At present， there is a lack of independent research and development of effective plugging agent materials for offshore oilfield operations. The development of liquid high-strength plugging agent was carried out through the optimization of the main agent and curing agent system. The curing mechanism of the plugging agent was studied by means of scanning electron microscopy and infrared spectroscopy，and the simulated plugging performance was evaluated through the settlement and curing experiments. Th results showed that the developed agent had a low initial viscosity of 90 mPa·s and a high sealing compressive strength，and has good settlement and curing properties，which resulting from the strong cross-linking reaction. it was confirmed that the plugging agent had excellent pressure bearing capacity（＞160 MPa/m）and could settle and cure at a height of 20 m，which has a strong plugging ability. The system had been applied to a horizontal well in A oilfield in the east of the South China Sea，and the leak point plugging operation had been successfully completed. This study provides a new pure liquid plugging agent for well integrity management， and the product has good application potential.