Ancient　wooden　buildings　and　structures　are　of　great　value　and　are　memorable　that　shall　be　protected　by　the　state　in　the　same　way　as　cultural　relics.　Based　on　Wireless　Sensor　Net　(WSN),　a　design　of　the　node　system　for　the　ancient　wooden　building　fire　prevention　is　presented.　Construction　of　Wireless　Sensor　Net　which　is　working　at　433　MHz　ISM　frequency　is　supplied　and　is　composed　of　PC　internet,　Coordinators,　nodes.　The　coordinator　is　based　on　ARM　s3c2440　microprocessor　and　Linux　operating　system,　which　can　communicate　with　PC　and　Internet,　and　can　communicate　with　node　system.　Nodes　can　communicate　with　each　other.　With　many　sensor　tags,　the　node　can　sense　environment.　Besides,　a　developed　software　tool　helps　to　improve　the　system　performance,　such　as　the　address　matching,　anti-collision,　checking,　identification,　and　real　time　calculation.　The　proposed　construction　has　advantages　of　simple　structure,　low　cost,　and　low　power　loss.　Problems　of　ancient　wooden　buildings　and　structures　which　have　been　protected　by　system　with　wire　line　have　been　resolved.　The　node　system　overcomes　the　difficulty　of　wire　lines　that　are　easy　to　be　fired.