In this paper, we report the results of RHEED, AES studies of thin Ge film grown on the patterned Si substrates which are formed by room temperature Ge deposition followed with thermal annealing to cluster the deposited Ge into islands. Double crystal X-ray diffraction measurements show that the existence of Ge islands on Si substrate surfaces is effective for releasing the mismatch strain and improving the crystalline qualities of the epilayers then deposited on it.