In this paper a detailed method is given to calculate atomic average of ionization in relativistic Hartree-Fock-Slater self-consistent field scheme. As an example，culculations are presented for the Au and Cu atoms at several temperatures (from 20eV to 20keV) and matter densities (from 0.1 D０ to 100D０). The variation of thedegree of ionization following the change of temperature and matter density are discussed.