Some　proton　conductors　such　as　solid　polymer　membrane,　zirconium　phosphate,　antimonic　acid　and　so　on,　kept　relatively　high　ionic　conductivity　even　at　room　temperature.　This　type　proton　conductor　sensors　for　detecting　combustible　gases　of　H2,　CO　and　C2H4　at　room　temperature　were　fabricated　and　studied.　We　here　described　their　structures,　sensing　mechanisms　and　performances.　The　effects　of　the　temperature,　humidity,　catalytic　electrode　materials　and　preparation　method　of　composite　electrode　on　the　sensor　response　were　also　discussed.　These　sensors　will　be　extensively　applied　to　the　petrochemical　industry,　environmental　protection　and　daily　life.