In　the　cement　industry,　SO2　and　NOx　are　generally　removed　separately.　There　are　many　problems,　such　as　large　area,　high　investment　cost,　secondary　pollution　and　so　on.　Desulfurization　and　denitrification　technology　have　become　a　frontier　research　direction　in　the　field　of　air　pollution　control.　In　this　paper,　rice　husk　ash　and　carbide　slag　were　compounded　and　modified　to　prepare　modified　rice　husk　ash-carbide　slag　composite　absorbent,　and　its　desulfurization　and　denitrification　performance　and　mechanism　were　studied.　The　results　showed　that　the　NO　conversion　and　SO2　conversion　of　the　modified　rice　husk　ash-carbide　slag　composite　absorbent　increased　by　44%　and　2%,　respectively,　at　700　°C.　Fibrous　calcium　silicate　and　calcium　silicoaluminate　hydrates　were　formed　during　the　hydration　process,　which　made　the　specific　surface　area　of　the　absorbent　larger　and　provided　more　reactive　sites.　The　hydration　process　increases　the　content　of　oxygen-containing　functional　groups,　decreases　the　hydroxyl/ether　C-O　functional　groups,　and　increases　the　content　of　carboxyl-COO　functional　groups　are　conducive　to　the　denitrification　reaction.