Abstract: In view of the cracking phenomenon of front water wall of a 600 MW supercritical W-flame boiler,the thermocouples on the fireside and backfiring surface of the water wall were installed. The influence of different location of the temperature and thermal load of water wall characteristics under the influence of the typical operating conditions,the oxygen concentration,the pulverized coal fineness and Fdampers opening under the process of boiler start-up and 600 MW load conditions was investigated. The test results show that due to the existence of the the angle of flame break,the flue gas flow is close to the front wall,the thermal load on the front wall is higher than that on the back wall under high load,and the thermal load on the front wall is the highest at 36.8 m,and the furnace width is up to 32 meters,which increases the possibility of water wall tearing. The F damper scale of rear wall pressing front wall can reduce the thermal load of front wall water wall as well as the possibility of water wall tearing. The thermal load decreases rapidly along with the furnace height. For the former wall,the average dimensionless thermal load at 36.8,44.0 and 48.5 m elevation of the former wall is 0.75,0.50 and 0.19 respectively.In the process of boiler start-up,the temperature difference between the the fireside and backfiring surface gradually increases,and the thermal load on the wall gradually increases after the pulverized coal is put into operation. Although the wall temperature of backfired surface has transient overtemperature when startingmill,the overall thermal load is low and the water wall is relatively safe. Oxygen concentration has little effect on the overall thermal load in the furnace. Under the condition of full load,the oxygen content is recommended to maintain at 2% under the premise of low CO concentration in the rear region. The thermal load decreases slightly after the pulverized coal become smaller. It is suggested that the scale of the folding dampers in condition 8 should be adopted without considering the coal mill output.