The　goal　of　Ambient　Intelligence　(AmI)　is　to　design　and　realize　the　brand-new　intelligent,　personalized　and　connective　systems　or　services.　According　to　the　requirement　of　natural　HCI　for　Ambient　Intelligence,　a　user　identity　sensing　technique　and　a　facial　orientation　estimation　method　are　provided　for　personalized　service.　(1)　To　make　ambient　intelligence　system　sense　users　in　or　out　and　identity　as　soon　as　possible,　an　approach　based　on　bluetooth　ad　hoe　network　with　Ethernet　is　proposed.　The　identifying　strategy　and　architecture　of　bluetooth　sensor　and　bluetooth　adapter　are　designed　and　the　details　of　key　technique　are　also　depicted.　(2)　Otherwise,　a　method　based　on　wavelet　analysis　technique　is　adopted　to　estimate　the　user＇s　basic　face　orientation　for　the　aim　of　personalized　automatically　driving　the　video　projector　to　rotate　toward　the　same　direction.　The　study　described　here　is　likely　to　be　used　in　intelligent　environment.