Selective　Catalytic　Reduction　as　an　efficient　technology　to　reduce　NOx　emission　has　been　widely　applied　in　exhaust　aftertreatment　system.　However,　the　reductant　injection　causes　inevitable　impingement　on　the　exhaust　pipe　and　mixer　surface　and　the　liquid　film　will　be　generated.　In　this　paper,　the　simulation　of　a　double-blade　mixer　(Mixer　1)　is　verified　by　a　bench　test　and　other　three　kinds　of　mixer　structures　(baffle　mixer:　Mixer　2,　blade-baffle　mixer:　Mixer　3,　and　blade　mixer:　Mixer　4)　are　simulated.　The　effect　of　the　mixer　structures　on　the　liquid　film　formation,　the　pressure　drop,　the　flow　and　temperature　distribution　after　the　mixers　and　ultimately　the　NOx　conversion　efficiency　are　investigated.　Results　show　that　the　liquid　film　is　prone　to　form　and　accumulate　at　the　connection　region　between　the　mixer　and　exhaust　pipe,　and　liquid　film　tends　to　develop　with　the　flow　direction.　Mixer　2　and　Mixer　4　shows　smaller　liquid　film　area　about　15　cm2.　The　temperature　distribution　in　four　types　of　mixers　shows　negligible　difference　(within　4　°C).　And　NH3　mass　fraction　distribution　uniformity　and　pressure　drop　show　a　trade-off　relationship.　For　the　vertical　injection　system,　it　is　found　Mixer　3　gets　the　worst　NOx　conversion　efficiency,　57%,　and　Mixer　2　shows　better　NOx　conversion　efficiency,　78%.　©　2022