This paper reports the effect of a high temperature (up to 1873 K) on the NO emission characteristics in an O-2/CO2 atmosphere. Two combustion mode experiments, separated combustion (volatile combustion and char combustion are separated) and coupled combustion (volatile combustion and char combustion are simultaneous), were conducted in a well-designed fixed-bed reaction platform to illustrate the interaction effect between volatile and char. The results show that the increase of the temperature leads to a noticeable fall and fluctuation of NO emission. Volatile NO emission decreases and fluctuates as the temperature increases, while char NO emission falls and is maintained at a low level at a high temperature. During the coal combustion process, two peaks of the NO concentration occur: a high peak at the initial stage and a low peak at the stage approaching the end of combustion. As the temperature rises, the effect of N redistribution caused by the interaction between volatile and char in the separated combustion becomes more significant than the effect of the gas-char heterogeneous reaction on the NO reduction to N-2 in the coupled combustion.