This　paper　designs　a　special　sensor　network　system　for　sewage　treatment　plant　based　on　MQTT　technology,　aiming　at　the　problems　of　remote　transmission　of　large　amounts　of　data　in　sewage　treatment　plant　and　interactive　use　of　various　industrial　protocols.　By　using　MQTT　protocol　to　upload　the　collected　data　to　the　cloud　server　and　multiple　protocol　fusion　method,　the　system　can　remotely　control　the　sensor　system　and　instrument　in　the　sewage　treatment　plant　and　realize　multiple　protocol　fusion　communication.　By　adding　edge　computing　and　reasonable　circuit　structure　design,　the　system　has　the　characteristics　of　strong　anti-interference,　good　explosion-proof,　high　safety,　and　has　the　advantages　of　maintenance,　easy　to　expand,　to　meet　the　needs　of　the　sewage　treatment　plant　site.　©　2022　IEEE.