In　order　to　make　best　use　of　wind　energy　resource　to　achieve　the　building＇s　natural　ventilation,　this　paper　develops　a　new　natural　ventilation　device,　the　automatic　wind　catcher,　based　on　the　torque　balance　principle.　The　device,　enabling　the　inlet　to　track　the　dominant　wind　direction　all　the　time,　makes　full　use　of　the　wind　pressure　and　the　principles　of　natural　ventilation　in　order　to　introduce　the　fresh　air　into　the　room　and　to　exhaust　the　dirty　air　out,　so　it　realizes　the　smallest　mechanical　ventilation　power　usage.　Experimental　results　show　that　when　the　device＇s　starting-up　wind　speed　is　0.5m/s,　and　the　outdoor　wind　speed　rises　up　to　1.5　m/s　or　higher,　the　device　can　track　any　point　of　the　dominant　wind　direction.　It　can　also　capture　a　certain　amount　of　outdoor　fresh　air　and　meet　the　needs　of　the　room＇s　comfortability.　The　good　aerodynamic　properties　and　the　mechanical　dynamic　characteristics　of　the　device　can　be　applied　in　areas　like　Beijing　where　the　average　wind　speed　can　be　as　high　as　2.8　m/s.　This　natural　ventilation　technology　can　be　used　to　achieve　building　energy　saving　and　emission　reduction.