The application of high temperature air combustion in incineration of solid waste was investigated. The combustion with preheated diluted secondary combustion air had effectively more energy saving and NOX emission reduction, but required a sufficient amount of preheated secondary combustion air to save more energy than non-dilution condition. The minimum preheated secondary combustion air temperature of 15 and 17% oxygen concentration conditions are 621 and 532 degrees C, respectively. The optimum condition is preheated-diluted secondary combustion air at 900 degrees C and 17% oxygen concentration and the operating ranges are preheated secondary combustion air above 621 to 900 degrees C and diluted between 15 and 21% oxygen concentrations.