Abstract: The deep formations of the Bohai Oilfield are geologically complex, and lost circulation has become a key issue restricting their efficient exploration and development. To address these challenges, a loss risk evaluation system based on multi-scale fracture identification and 3D in-situ stress field simulation was established, enabling prediction of lost circulation risk and well trajectory optimization. By integrating seismic, geological, and engineering data, the casing program was optimized to avoid simultaneous drilling through weak and high-pressure formations. Precise managed pressure drilling (MPD) and cementing technologies were applied to precisely control wellhead back pressure (±0.07 MPa), enhancing safety during drilling and cementing operations. In addition, lost circulation additives capable of withstanding high temperatures (220 °C) and high pressures (20 MPa) were developed. Ultimately, a comprehensive lost circulation control technology system was formed, characterized by “zonal treatment, prevention-oriented strategy, and combined control and plugging”. This system has been successfully applied in over ten deep exploratory wells in Bohai Oilfield, and both research and field results demonstrated strong adaptability and effective sealing performance of the system, with a one-time plugging success rate exceeding 80%. The proposed system provides reliable technical support for safe and efficient deep drilling in Bohai Oilfield and holds potential for broader application in other offshore deep oil and gas drilling in China.