Mentalizing　is　an　essential　component　in　human　social　interactions　and　the　sources　of　individual　variation　in　mentalizing　are　still　very　poorly　understood.　Utilizing　the　＂reading　the　mind　in　the　eyes＂　test　(RMET),　we　examined　the　neuroanatomical　basis　of　these　differences　with　voxel-based　morphometry　and　found　that　the　gray　matter　density　in　the　left　posterior　superior　temporal　sulcus　(pSTS)　could　positively　predict　individuals＇　RMET　scores.　Furthermore,　we　found　that　the　pSTS-amygdala　functional　connection　was　positively　correlated　to　individuals＇　RMET　scores.　A　test-validation　procedure　confirmed　that　the　imaging　results　could　be　replicated　and　validated　in　another　independent　sample.　Finally,　mediation　analysis　revealed　that　pSTS-amygdala　functional　connection　could　account　for　the　relationship　between　pSTS　gray　matter　density　and　RMET　scores.　Present　results　demonstrate　the　contribution　of　brain　structure　of　pSTS　to　individual　variations　in　RMET　performance　and　reveal　an　important　implication　of　the　neural　circuit　between　core　imitation　and　emotion　regions　in　REMT.