Nickel-palladium film on p-Si prepared by potential -controlled electrodeposition has much better adherence than that deposited by other methods .To reveal the reasons of this effect ,X-ray photoelectron spectroscopy (XPS) combmed with Ar+sput tering was used to investigate the interface of NiPd /Si .The results showed that dramatic interdiffusion of Ni, Pd and Si had occurred at atmospheric temperature .On the XPS spectra of mckel and palladium ,there are two kinds of binding energy ,contributed by pure metals and metal silicide respectively. NiSi, PdSi and Pd2Si were formed at the interface. Both of the electric field on the surface and the H atoms in the metal lattice have the possibility to promote reactions between nickel or palladium and silicon .