Abstract: Objective Aiming at the problems of high carbon emission intensity and low energy efficiency during offshore oil and gas field development, as well as the challenges including high development cost and insufficient power consumption accommodation of deep-sea new energy, this paper studies the engineering modes of multi-energy complementary integrated development of offshore new energy and oil & gas, so as to provide technical routes and practical references for the green and low-carbon transformation of marine energy. Methods Guided by national energy policies and based on China’s marine energy resource endowments, this paper systematically sorts out the industrial status of integrated development of offshore new energy and oil & gas, and analyzes core industrial challenges such as equipment limitations, power grid stability risks, immature commercial operation modes and insufficient overall marine resource coordination. Comprehensive comparative analysis is carried out from the perspectives of technical principles, equipment systems, applicable scenarios, economic costs, emission reduction benefits and operation & maintenance characteristics. Results Six core integrated engineering modes are established and elaborated, including fixed wind power integration, semi-submersible floating wind power integration, tension leg floating wind power integration, ocean thermal & geothermal energy integration, multi-energy reconstruction of decommissioned platforms, and integrated mode of offshore new energy coupled with computing power and oil & gas. The six modes can cover all offshore oil and gas development scenarios ranging from inshore to deep sea, and stock to incremental projects. Engineering practices have fully verified the feasibility and advancement of multi-energy integration. Modes with mature technologies and favorable economic benefits such as inshore fixed wind power integration and deep-sea semi-submersible floating wind power shall be prioritized for popularization. Large-scale offshore green power replacement projects shall be promoted by relying on existing oil and gas zones to cut carbon emissions of oil & gas production and build batches of green oilfield demonstration projects. Technical iteration and large-scale application of large-capacity tension leg floating wind power shall be accelerated to build benchmark bases for large-scale multi-energy integration in deep waters. Conclusion The integrated development of offshore new energy and oil & gas serves as a vital approach for the green and low-carbon transition of marine energy, which can greatly reduce carbon emissions from oil & gas exploitation and improve the economic efficiency of new energy development. It is recommended to accelerate research on key technologies and perfect the system of policies and standards, and advance large-scale demonstration applications.