Titanium alloys and nickel-based alloys have unique properties. The bimetallic structure formed by them has a broad application prospect in the aerospace field. However, due to the large differences in physical and chemical properties between the two metals, cracking is easy to occur at the bonding zone. Based on directed laser deposition (DLD) technology, TC4/IN718 bimetallic structures without interlayer and Cu interlayer were fabricated, respectively. The resuslts of test and analysis results indicate that the TC4/IN718 bimetallic structure without interlayer has cracking due to the formation of the Ti-Ni brittle phases at the bonding zone, which leads to the increase of crack sensitivity. In the bimetallic structure with Cu interlayer, the Cu transition zone formed between TC4 and IN718, which inhibited the direct combination of TC4 and IN718 and reduced the crack sensitivity. Due to metallurgical reaction and element diffusion, a small amount of Ti-Cu and a very small amount of Ti-Ni compound phases are formed in the Cu transition zone. Due to the formation of the compound phase, the Vickers hardness of the transition zone of TC4/IN718 bimetallic structure with Cu interlayer is about 592 HV. However, it is much lower than the Vickers hardness of the bonding zone of TC4/IN718 bimetallic structure without Cu interlayer (about 845 HV).