The aim in this work is to establish an overall symmetrical combustion setup for a 600 MWe supercritical down-fired boiler via evaluating effects of various factors (related with the upper furnace parameters and combustion system) on asymmetric combustion. Firstly, based on comparing the flow-field symmetry and performance parameters at the furnace outlet, effects of various factors (such as the dimensionless upper furnace height C-H2, boiler nose depth C-L, upper/lower furnace depth ratio C-w, furnace arch's burner location C-D, burner span C-s, and staged-air angle theta) were numerically determined under coal-combustion conditions. Secondly, three combined setups that considering all these factors were numerically compared. With C-w and C-D fixed at the boiler's design levels, applying an integrated solution consisting of lengthening upper furnace to C-H2 = 1.125, shortening burner span to C-s = 0.387, and performing a sharp staged-air declination, developed symmetrical combustion plus apparent improvements in burnout and NOx emissions. Under these circumstances, maintaining C-L at its original value of 0.298 and meanwhile setting theta at 45 degrees, which corresponded to the combined setup 2 in this work, attained the best performance parameters at the furnace outlet. In view of the cold-modeling experiment also confirming the symmetrical gas/particle flow-field formation, the combined setup 2 was finally recommended as an overall symmetrical combustion setup for the down-fired boiler. (C) 2018 Elsevier Ltd. All rights reserved.