Using Hartree-Fock-Slater potential instead of Thomas-Fermi potential, a normalized formula of electronic stopping power is derived. Combined with the idea of effective atomic number, a correlate formula of electronic stopping power Se(E) and energy is obtained. The oscillation of Se(E). with atomic number of ions or target atoms are quantitatively calculated on the basis of the former formula. The results coincide well with experimental data in the literature. By using the later formula, the Se(E) of a variety of ion-target systems are quantitatively calculated. As compared with the formula in reference 1, the present results agree more satisfactorily with the experimental values and fit a broader range of energy.