The initial nickel deposition for the direct electroless nickel plating on active SiCp/Al composites is critical. So it is necessary to investigate the process of the electroless Ni-P plating deposition on SiCp/Al composites by means of scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). In addition, the mass gain/loss in the initial nickel deposition process was measured by using the electro-balance. The results show that after being treated using phosphoric acid and hydrogen peroxide, the compositions of SiCp/Al composites substrate contains Al, SiC and Al2O3. The Al2O3 film was gradually corroded by the plating solution. And then Ni-P coating was deposited on the substrate without Al2O3 film during the initial electroless plating process, which was mostly growing on the boundary between the SiC particles and the Al crystal of the activation substrate, and then came to two sides. After that, the Ni-P coating growth rate to cover with the SiC particles and Al crystals was prior to the Al2O3 film. The electroless plating was in company with the substrate corrosion, but the electroless plating rate catalyzed by the exchanged nickel was more than the substrate corrosion rate.