As increase of natural gas treatment plant units and their capacity,it is necessary to study combustion process in low temperature Claus sulfur recovery and tail gas treatment unit and effects of various factors on the process so as to provide basis for engineering design. Based on industrial operation experience for a long term,analyzed is incinerator temperature, adopted is thermodynamic model to conduct theoretical calculation of residence time and staged combustion air ratio coefficient in combustion process, compared are effects of different parameters on combustion results in combustion process and proposed are the optimum furnace temperature, residence time and the best suitable staged combustion air ratio.