Abstract:China’s relevant standards stipulate that the volume of the main control temperature zone in the incinerator furnace should meet the requirements that the residence time of flue gas above 850℃ is greater than or equal to 2s under the most unfavorable conditions. At present, the main control temperature zone of mechanical grate furnace in domestic waste incineration power generation industry mainly has two types: single flue and main and auxiliary flue. In this paper, by studying the relevant specifications and combining the characteristics of these two types of furnaces, the calculation of flue gas residence time of single flue and main and auxiliary flue was discussed, especially for how to meet the requirements of 850℃/2s for the flue gas residence time of the incinerator with the main and auxiliary flue, the starting point of the calculation was analyzed and studied, and the solution to the controversial point was given.