A submerged floating tunnel (SFT) has been considered as an interesting structure to connect the banks separated by a narrow and deep sea. Governing load of a SFT is bending moment, a structure with enhanced stiffness and ductility will be useful for a SFT. Therefore, new-type structures which have superior stiffness and ductility were proposed for the SFT using composite Hollow RC structure. The cast-in-place concrete can’t apply for construction, because SFT will be constructed underwater. For this reason, SFT is constructed onsite after making module segment on coastal factory. In this paper, connection method of module segment for SFT is proposed using PC tendon. It is verified by experimental study. Bending test of module segment specimens are evaluated, and the proposed connection method has good performance.