The first 1 000 MW coal fired supercritical variable pressure operation boiler with vertical furnace waterwall has achieved the following successful results. This paper describes the design features and trial operation results of this boiler. (1) High reliability of vertical furnace waterwall with rifled tubing. (2) NO_X of 150 ppm and 3% of unburnt carbon in fly ash by advanced combustion technology with low NO_X burner, in-furnace NO_X reduction system and high fineness pulverizer. (3) High boiler efficiency of 91.61 % by optimization of combustion system.