During the secondary welding process of titanium-steel hybrid structures for ships, repeated thermal cycles inevitably change the interfacial microstructure and mechanical properties of explosive-welded transit joints. These changes directly affect the bonding strength of hybrid structures and navigational safety of ships. Herein, simulated transient heat treatment (STHT) was adopted to study the relationship among temperature, interfacial microstructure, and bonding properties of a titanium-steel hybrid structures during the secondary welding process. Results showed that when the STHT temperature was <600 ^oC, the interfacial microstructure remained stable. Meanwhile, at ≥ 700 ^oC, recrystallization occurred, causing grains near the interface to become coarse. Furthermore, the thickness of the intermetallic compound layer comprising FeTi and TiC increased rapidly. Unlike aluminum-steel hybrid structures, in which the interfacial bonding strength monotonically decreases with increasing temperature, the bonding and shear strengths of the titanium-steel hybrid structures initially increased and then decreased, with peaks appearing at 500 and 600 ^oC. The thermal effect at medium and low temperatures promoted atomic diffusion and stress release, thereby improving the interfacial bonding strength. At high temperatures, grain coarsening and intermetallic compound growth decreased the bonding strength of the transit joint. Overall, the critical threshold temperature at the interface of the titanium-steel hybrid structures is 600 ^oC.