In this study, a direct transition TA15/GH4169 dual alloy composite structure is prepared using the laser deposition manufacturing technique at preheating substrate temperatures of 100 ℃ and 400 ℃. Further, the effect of the preheating temperature on the microstructure, residual stress, and microhardness of the TA15/GH4169 interface is investigated. Based on the results, substrate preheating can be concluded to considerably influence the forming quality of the composite structure, whereas the non-preheated substrates produce defects at the composite structure interface. The forming quality improves when the preheating temperature is 400 ℃, and a gradient transition zone of approximate 0.33 mm is formed at the composite structure interface. The residual stress on the GH4169 side significantly decreases when the preheating temperature is increased from 100 ℃ to 400 ℃. The residual stress value reduces by 21.59% when the substrate is preheated to 100 ℃, whereas it reduces by 33.19% when the substrate is preheated to 400 ℃. The microhardness of the composite structure slightly decreases with an increase in the preheating temperature. At the same preheating temperature, the microhardness of the transition zone is the highest. At 400 ℃, the microhardness of the transition zone increases by 91.2% compared with that of the TA15 side.