The　electronic　structures　and　ionization　potential　of　C4S4m-　(m=0,1,2,3,4)　are　calculated　at　the　RHF(UHF)/6-31G,　RKF(UHF)/6-31G*　and　RHF(UHF)/6-31+G　levels　using　ab　initio　SCF　and　Boys　localized　molecular　orbital　(LMO)　approaches.　The　characteristic　of　bonding　and　the　relationship　between　ionization　potential　and　corresponding　Delta　E-SCF　are　discussed.　Vibrational　frequencies,　IR　intensities,　intrinsic　frequencies　and　force　constants　have　been　calculated　at　the　6-31G　level　by　analytical　second　derivatives　at　the　optimized　equilibrium　geometries.　The　results　of　the　electronic　structure　and　Boys　LMO　calculations　and　the　vibrational　analyses　are　consistent　with　the　optimized　equilibrium　geometries.