Abstract: Scanning electron microscopy (SEM), atomic force microscopy (AFM) and energy dispersive spectrometer (EDS) were used to observe and analyze the morphology of nodulation on the back of the blade and the surface morphology and composition evolution during the treatment of the aluminum alloy matrix before electrodeposition, and the formation mechanism of nodulation on the back of the blade was investigated. The results show that during the pretreatment, the aluminum alloy around the precipitates on the surface of aluminum alloy matrix dissolve gradually, and the precipitates fall off. After twice zinc dipping, the aluminum matrix surface generates 0 to 6 μm holes. The nickel deposit in the holes during the electrodeposition of nickel-diamond composite. After removing part of the aluminum alloy matrix, the 0 to 6 μm bumps are formed on the back of the deposit layer, i.e. nickel nodules.