依托厦门市轨道交通3号线跨海隧道工程，分析了超长跨海隧道的工程特点、功能需求，针对特点和需求，从地质选线、工法选择和结构设计等方面，阐述了超长跨海隧道的土建方案设计理念，重点对施工采用“盾构+矿山+盾构”的组合工法、海域区间通风排烟道方案、风井位置选择和隧道结构断面形式选择进行了介绍。并对大小洞组合方案、三洞组合方案和单大洞方案进行了方案比选，最终确定采用大小洞方案。最后，对海底盾构与矿山对接、海底超长地铁隧道防灾救援、高水压跨海隧道结构防排水措施等关键技术问题进行了初探并提出了进一步研究的建议。

In this paper, the engineering characteristics and functional requirements of the superlong seacrossing tunnel on No. 3 Line of Xiamen Metro are analyzed. The concept of the civil scheme design of the superlong seacrossing tunnel is presented in terms of geologybased route selection, construction method selection and structural design. The construction method of “shield boring method + mining method + shield boring method”, the scheme of the ventilation and exhaust discharge gallery of the seacrossing section, the selection of the ventilation shaft location and the type of the structural crosssection of the tunnel are presented in detail. Comparison and contrast is made among the scheme of “large crosssection tube + small crosssection tube”, the scheme of “three tubes” and the scheme of “single large crosssection tube”, with the scheme of “large crosssection tube + small crosssection tube” adopted in the end. Furthermore, the construction technologies for the connection between the shield boring section and the mining section, the technologies for the disaster prevention and rescue of the superlong seacrossing Metro tunnel, and the structural waterproofing and drainage technologies of the seacrossing tunnel under high water pressure are studied and discussed, and some suggestions are given.