Abstract: Based on an amendment of ionization potential in hydrogen-like ions in terms of the theory of relativity and interaction of electron spin-orbit,we take into account the effect of the nuclear volume and the nuclear mass for the ionization potential.Some ionization potentials in hydrogen-ions are calculated.Our results are in well agreement with the experiment data.The present method can make up the deficiency of other methods.

Key words: relativity effect, mass effect, volume effect, ionization potential