Affected by factors such as broken surrounding rock and large amount of water seepage, there are huge risks such as water inrush, mud inrush, and collapse when a mining tunnel passes through a water-rich fault zone. Based on a subsea tunnel project in Qingdao, this paper studies the full-section advanced curtain grouting construction method commonly used when mining tunnels pass through the water-rich fault zone. Specific measures such as slurry type and ratio, improvement of grouting equipment and grouting process can optimize the grouting process. The rationality and effectiveness of the curtain grouting optimization measures were verified by drilling inspection holes and comparing monitoring and measurement data, achieving the expected results, meeting the subsequent excavation conditions, and providing reference and guidance for the construction of similar projects.