Abstract: To solve the problems of high CO emission concentration at furnace outlet and coking at flue gas exhaust outlet existing in a 670 MW octagonal corner tangentially-fired tower boiler burning low calorific value lignite, numerical simulations and experimental tests were conducted to study the effects of the following factors on the in-furnace temperature field, and the O₂, NO_x and CO concentration distribution, such as the vertical swing angle of SOFA, the SOFA volume and the SOFA speed, etc. Results show that the increase of SOFA air velocity can effectively reduce the flue gas temperature and CO concentration at furnace outlet. Compared with case 1, the outlet CO concentration of the furnace in case 6 has been reduced from 0.291 2% to 0.025 7%, with a reduction of flue gas temperature at furnace outlet by 43 K, a reduction of exhaust gas temperature by 6 K, an increase of boiler efficiency by 0.63%, and a reduction of standard coal consumption by 2 g/(kW·h), while the NO_x emission concentration basically keeps unchanged at furnace outlet.