Based on the non-uniform gas-solid flow of large-scale circulating fluidized bed (CFB) boilers, an innovative polygon furnace technology was put forward. Combined with cold test, numerical calculation and boiler tests, the effects of three polygonal furnace structures on the uniformity of gas-solid flow and particle concentration distribution were investigated. The research results show the furnace adopts the chamfered-corner structure, the circulating flow rates of three circulation loops are greatly increased, there is no obvious particle agglomeration phenomenon in the chamfered corners center of the furnace, and the non-uniformity of the gas-solid flow and particle concentration distribution can be effectively improved. The maximum relative deviation of three cyclones inlet and outlet flue gas temperatures for 350 MW supercritical CFB boiler is less than 6.0%, and the temperature distribution of the furnace and three cyclones is relatively uniform, the technology demonstration of the first 350 MW supercritical CFB boiler with polygonal furnace is successful. (C) 2019 Elsevier B.V. All rights reserved.