Based on the design and construction experience of rivercrossing tunnels, subsea tunnels, long tunnels and highspeed railway tunnels, the author concludes that the reasonable option for Taiwan Strait subsea tunnel is railway tunnel. The crosssection types and areas, portal types and construction schemes of Taiwan Strait subsea tunnel are recommended in the paper. The author presents the situation of construction of rivercrossing tunnels and subsea tunnels in China. Moreover, the author provides some new concepts, including the idea that rivercrossing tunnels and subsea tunnels have more advantages than bridges. At last, the author presents the key technical problems that need further researches in the construction of subsea tunnel.