Using first-principles method the adsorption properties of An on clean and H-Si(001) surface were investigated. The results showed that adsorbed Au atoms could break Si-Si dimer bonds of the substrate on the clean Si(001) surface. The adsorbed Au atoms will stay on Si(001) surface at low temperature and they can diffuse into the substrate at relatively higher temperature due to the small energy barrier. The adsorption of An on H-Si(001)surface can not break Si-Si dimer bonds of the substrate which is contrary to the property of Au on clean Si(001)surface.