The　B3LYP/6-311　+　G　(3df,　2p)　method　of　density　functional　theory　is　used　to　investigate　the　equilibrium　structures　and　stabilities　of　the　chain　HSSX(X　=　H,F,Cl,Br)　and　branched　SSHX(X　=　H,F,Cl,Br)　isomers.　The　calculated　results　show　that　the　chain　structures　are　more　stable　than　the　corresponding　branched　ones(e.　g.,　lower　in　energy　by　109.8,　60.2,　74.8　and　73.1　kJ/mol　after　zero　point　vibrational　energy　correction,　respectively).　The　thermodynamic　analysis　also　demonstrated　that　the　possibility　is　rather　low　for　the　branched　structures　to　isomerize　to　the　chain　ones.