Abstract: With the accelerated development of global marine resources towards deep-sea and polar regions, heavy equipment such as deep-sea drilling platforms is rapidly advancing. Structural components exhibit an increasing trend towards larger size and higher strength, which impose greater demands on offshore engineering structures and welding performance. Electro-gas welding, leveraging its high heat input characteristic and exceptional single-pass penetration capability, significantly enhances welding efficiency and demonstrates considerable value in the technological evolution of welding thick plates for offshore engineering. This article elucidated the metallurgical mechanisms of high heat input resistant offshore steels, reviewed the development history and challenges of high heat input electro-gas welding technology, introduced its research progress and current engineering application status in offshore equipment manufacturing, and discussed its future trends and key research directions. The aim is to provide a reference for the application of high heat input electro-gas welding technology in the field of offshore engineering manufacturing.