通过总结我国公路水下隧道地质勘察设计经验，结合钻爆隧道、盾构隧道、沉管隧道及堰筑隧道4种水下隧道建设工法的设计与施工特点，提出水下隧道地质勘察成果不仅应满足各设计阶段的要求，而且还应满足工法的需要。强调地质勘察质量取决于勘察方案的合理性、勘察手段的针对性以及勘察成果的完整性。制订切合实际的地质勘察方案，投入与各阶段设计深度相适应的地质勘探工作量，对提升地质勘察工作的质量和保证工程安全至关重要。通过综合分析，给出了不同地质条件下各类水下隧道的合理勘探方法与应达到的勘察深度，对提高水下隧道工程质量与安全具有参考价值。

In this paper, the geological investigation and design technologies for underwater highway tunnel are summarized; the characteristics of design and construction of drilling and blasting tunnel, shield tunnel, immersed tunnel and cofferdambuilt tunnel are proposed. The author suggests that the investigation results of underwater tunnel have to meet the requirements of design and construction of the tunnel; the geological investigation quality is decided by investigation scheme, method and results; the rational geological investigation scheme and relative investigation works are the keys to geological investigation and the engineering construction. The rational geological investigation methods and depths for underwater tunnels under different geological conditions are proposed. The results can provide reference for quality and safety of construction of underwater tunnels in the future.