In　the　process　of　degradation　of　toluene　by　plasma　assisted　catalysis,　ozone　is　generated　from　reactive　oxygen　atoms　along　with　the　pollutants　degradation.　The　changes　of　ozone　concentration　and　degradation　of　toluene　under　different　catalysts,　discharge　energy　levels,　catalytic　section　lengths　and　gas　velocities　were　compared,　and　the　formation　of　ozone　in　the　process　was　explored.　The　results　showed　that　the　7.5%Mn/cordierite　catalyst　placed　in　the　discharge　zone　could　inhibit　the　generation　of　ozone,　promote　the　degradation　of　toluene,　and　improve　the　energy　efficiency　of　the　system　effectively.　The　maximum　concentration　of　ozone　was　reduced　by　63.32mg/m3,　compared　with　that　without　the　catalyst.　However,　the　catalytic　performance　of　0.2%Pd-0.3%Ce/cordierite　on　toluene　degradation　and　ozone　inhibition　was　poor.　With　the　increase　of　the　energy　level　of　the　system,　the　degradation　rate　of　toluene　and　the　ozone　concentration　increased　gradually.　The　Ozone　concentration　was　positively　correlated　with　the　length　of　catalytic　section,　but　negatively　correlated　with　gas　velocity.　Under　different　voltages,　the　ozone　concentration　firstly　increased　and　then　decreased.　When　the　applied　voltage　was　13kV,　the　ozone　concentration　was　the　highest,　but　it　decreased　to　zero　when　the　voltage　was　raised　up　to　16kV.　©　2020,　Chemical　Industry　Press.　All　right　reserved.