The initial corrosion behavior of SiCp/Al composites in Cl- containing solution was inverstigated by using immersion test and Scanning Kelvin probe (SKP) technique. The results show that the initial corrosion is preferential to occur at the interface between SiC particles and Al matrix of SiCp/Al composites in Cl- containing solution. Cl- and interfacial phase is responsible for the development of initial corrosion. The passive film formed in the initial stage, while the surface potential of SiCp/Al composites moved positively. When the corrosion process continued, the passive film finally breakdowned, resulting in the negative shift of the surface potential. The main corrosion products are Al(OH)3, Al2O3 and AlCl3.