Abstract: Based on the atomic and molecular reaction statics, the ground electronic states for Se2（3Σg）, Se2+（2Πg）,Se2-（2Πg）and Se22+（1Σg）and the corresponding reasonable dissociative limits were derived. Using density functional method (B3LYP)and 6311G** basis sets, the molecular equilibrium geometry and dissociation energy for Se2x（x=0,+1,-1,+2） were calculated. Then, with MurrellSorbie function form, spectroscopic date for Se2x（x=0,+1,-1,+2） were derived. The calculated results for Be, αe, ωe and ωeχe are 0.0790, 0.0002, 379.5760 and 0.9309 cm-1 respectively for Se2, 0.0849, 0.0002, 464.0401, 0.9754 cm-1 respectively for Se2+, 0.0564, 0.0002, 323.0775 and 0.8482 cm-1 respectively for Se2; 0.1001, 0.0001, 603.4454 and 0.0299 cm-1 respectively for Se22+, which are in good agreement with experimental or calculated values in references. It shows that Se2, Se2+, Se2- and Se22+can be stable.