Nanosized　powder　zircon　as　a　new　ceramic　material　are　used　in　many　fields.　This　paper　introduced　how　to　prepare　the　nanosize　zircon　in　a　low-temperature　super　alkaline　condition,　and　to　fabricate　the　sensors　by　using　this　material　with　different　doping.　The　sensor　is　sensitive　to　humidity　and　NH3,　with　characters　of　fast　response　and　recovery　in　good　time.　The　structure　of　the　sensor　is　simple,　and　the　sensor　is　easier　to　be　made　than　other　sensors.　The　capacity　of　the　sensor　obviously　changes　with　the　humidity,　but　less　responses　to　temperature　variation.　As　a　conductance　type　gas　sensor,　the　component　is　well　selective　to　NH3.