Nanocomposite　K-Co-CeO2　catalysts　were　synthesized　by　the　controllable　micropore-diffused　co-reaction　method.　Due　to　the　size-match　nanometre　effect　between　CeO2　support　and　active　components　and　formation　of　NO2,　these　cheap　nanocomposite　catalysts　exhibit　super　catalytic　performances　which　are　as　good　as　a　supported　Pt　catalyst　under　loose　contact　conditions　for　soot　combustion.