In order to achieve the explosion-proof function, most of the blast blower impellers use casting copper alloy as a whole component. This method consumes lots of manufacturing resources and is also expensive. The cladding of copper alloys on the surface of casting ironed impellers by L-DED (Laser Directed Energy Deposition) can effectively reduce resource consumption and save costs. However, the huge difference in physical properties between cast iron and copper alloys, coupled with the extremely low laser absorption of copper alloys lead to defects such as oxidation, cracking and difficulty in L-DED process. To achieve high-quality L-DED copper alloys on casting iron surfaces, the effect of temperature gradient control strategies such as preheating and slow cooling processes on the quality of L-DED were investigated. Additionally, we evaluated the effect of transition layers of NiCrBSi and Inconel 718 on deposition quality, by analyzing microstructure morphology and measuring the microhardness at the bonding interface. The study also covers the completion of L-DED process path planning for complex impeller surfaces. Ultimately, employing a preheating and slow cooling process and selecting suitable transition layers enabled successful achievement of L-DED CuSn15 alloy on the surface of a cast iron impeller, devoid of cracks, holes or other defects.