The Photoelectron Spectroscopy(PES) and different ionic state of SiBr~4 were reported in this paper. The ionic states of SiBr~4^+ are X^2T~2, A^2T~1, B^2E, C^2T~2 respectively. The adiabatic ionization potential of the compound is I~a(X^2T~2←X^1A~1)=10.532eV. a frequency of (450±30)cm^-^1 was observed in the PES band of X^2T~2 ionic state. The assignment of the PE spectrum was performed with the help of the theoretical calculations and the band characters. obvious Spin-Orbital Coupling split was observed in X^2T~2 and A^2T~1 states, and the splitting space are 0.27eV and 0.53eV. The comparison of different calculations shows that the Outer Valence Green's function (OVGF) method gives quite good results in ionization potentials calculations.

Key words: ELECTRONIC STRUCTURE, IONIZATION ENERGY