Abstract: Compared with the SCR-De NOxsystem of high temperature and high dust area arrangement,the arrangement of high temperature and low dust area has obvious advantages in protecting catalyst and air preheater.An integrated technology of high temperature dedusting and denitrification was proposed,which combined high temperature electric bag composite dust collector and SCR denitrification reactor.Three types of flow in and out of the denitrification reactor,including lower flow in and upper flow out,side flow in and side flow out,upper flow in and lower flow out were compared and analyzed.The results show that the first type has the advantages of simple structure and high economy.At the same time,,using a 350 MW unit as an example,the numerical simulation of high temperature dedusting and SCR-De NOx integrated device was carried out by using Fluent software.The flow field distribution inside the device was analyzed,and the optimized design scheme was proposed. The simulation results show that the flow field distribution in device can be improved and the vortex in the flue can be reduced by improving flue structure and design diversion measures( flue deflector,rectifier grille,adjusting orifice opening rate,ash-bucket baffle,etc.).After optimization,the velocity distribution variation coefficient at inlet section of AIG,the first electric field,the1 st catalyst and air preheater are decreased from 27.1%,12.1%,38.8%,17.6% before optimization to 22.4%,22.3%,5.5%,11.3%,respectively.And,the ammonia concentration distribution variation coefficient and the flue gas incidence angle at inlet section of the 1 st catalyst are reduced from 15.0% and 172° before optimization to 3.8% and 5.3°,respectively,so as to meet relevant technical requirements of flow field,and provide reliable guidance for engineering design.