Abstract: To investigate the distribution characteristic of melting temperature of ash deposits deposited on different locations of furnace wall, comparison test on two combustion work conditions was made in trial furnace of black liquor coal slurry. Analysis was made on melting temperature, chemical composition, and mineral phase of ash deposits on furnace wall along journey of fume. The result shows that melting temperature of ash deposits at 155mm from outlet of burner on furnace wall is the lowest, and that of the highest is in the regions of 1000mm~1150mm from outlet of burner. Melting temperature of ash deposits on furnace wall assumes the distribution characteristic of elevation at the start followed by degradation gradually. Such distribution characteristic is correlated directly with transportation and deposition of mineral elementals, and related with combustion heat load to a certain degree.