By intentional introduction of Ni on Si(1 0 0) and Si(1 1 1) we have observed the reconstruction of the both surfaces. Scanning tunneling microscopy studies reveal morphologies of the Si(1 0 0)-2 x n structure, which are partially different from those of the reported up to now. Heterogeneous reconstruction has been also observed on Sill 1 I) surface: the 7 x 7 terraces and terraces being composed of disordered adatoms distribute alternatively on the surface. We present the results and give our primary exploration to their formation mechanism.