The Middle East is a vital region for global offshore oil and gas development, characterized by high design standards, complex international procurement, and significant construction technical challenges in offshore oil engineering EPCI(Engineering, Procurement, Construction, and Installation) projects. A case study of an EPCI project in the Middle East systematically analyzes the critical role of design management throughout the project lifecycle. By integrating the design, procurement, construction, and installation phases, a management strategy centered around design leadership is proposed. Emphasis is placed on practical methods such as design integration, interface coordination, change management, and supply chain optimization. By preemptively aligning subsequent phase requirements with the design stage, significant reductions in project costs and risks can be achieved. Given the unique context of the Middle East, recommendations include employing a strong matrix human resource allocation model, a dynamic lessons-learned database, and localized stakeholder management mechanisms to enhance project execution efficiency effectively. This provides valuable insights and references for Chinese energy enterprises undertaking international contracting projects in complex environments along the "Belt and Road" initiative.