Aspects of bridge and tunnel are analyzed and their characteristics are compared,such as aviation and shipping, traffic capacity and driving comfort, road safety and climate adaptability,construction difficulty and project risk, etc. Technically, schemes of bridge and tunnel are both workable. Tunnel scheme is privilege to bridge scheme on aviation, shipping, climate adaptability, ecological environment and so on. While bridge scheme has advantages over tunnel scheme on traffic capacity, construction difficulty and risk, operating costs, driving safety, driving comfort, landscape and so on. Comparative evaluation index system for Bohai Strait cross-sea channel is structured by analytic hierarchy process. And weight coefficients of every index are calculated. Membership grade of every qualitative index is calculated by experts scoring method and membership grade of every quantitative index is calculated by membership grade function. Finally, model of fuzzy comprehensive evaluation is used to calculate comprehensive evaluation value of full bridge scheme, full tunnel scheme and combination scheme of bridge and tunnel. Comprehensive evaluation value of full tunnel scheme is maximum and the full tunnel scheme is the recommended scheme for Bohai Strait cross-sea channel.