The key technological issues related to Taiwan Strait Tunnel, including geological and topographic conditions, alignment selection, seacrossing transportation modes, durability, construction methods, necessity to build service tunnel and the functions of service tunnel, are summarized. The advantages of and the problems in building the sea crossing tunnel are analyzed briefly. This paper points out that it is fundamental to make a proper final choice from the bridge option and the tunnel option. The construction scheme and construction schedule related to the tunnel solution are discussed. It is proposed that scheme 1, i.e., the 5.5 m service tunnel is driven first, then 8.0 m TBMs and their backup systems for the main tunnels are taken apart into several parts,from the first to through the service tunnel and the cross passage opening and are then assembled in the main tunnels before the main tunnels are driven by the TBMs, should be adopted, and that scheme 2, i.e., the 5.5 m service tunnel is driven first, then 5.5 m TBMs and their backup systems for the main tunnels are taken apart also into several parts only when it passing through the cross passage opening, delivered into the main tunnels and assembled to bore 5.5 m pilot tunnels at first, and thereafter are enlarged to 8.0 m main tunnel by drill and blast method, be adopted as standby. It is estimated that, in the case of scheme 1, the total construction period of the 150 kmlong Taiwan Strait Tunnel should be about 30 years.