Abstract: The tetrahedrone molecules contaning elements Mof the grop IVhave received considerable attention both experimentally and theoretically, since they are new type compounds and reveal some special properties in chemistry. Following a suggestion by J. C. Slater, the SCF-Xa-SWmethod which was developed by K. H. Johnson is ideally suited for calculation of molecular photoelectron spectroscopy, because the transition state theory was adopted in the method, having corrected the frozen orbital approximation in Koopmans' theorem. The computer program, XASW, VAX-IBM VERSON 1, was used in the study and carried out on Siemens-7760 computer. The X_a theoretical values of ionization potential calculated in this paper are in good agreement with the experiment ones.