We have established the instantaneous governing equations for NO release during char combustion of nonspherical particles theoretically. The instantaneous released NO mass variations, the instantaneous char oxidation reaction rates, and the instantaneous NO reduction reaction rates of char particles were computed numerically under different fluctuation amplitudes of gas temperature, kinetic parameters of char oxidation reaction and NO reduction reaction, and particle aspect ratios. The gas temperature fluctuation results in a faster NO release rate, a faster char oxidation reaction rate, and a faster NO reduction reaction rate during the whole char combustion processes. The activation energy of char oxidation reaction has obvious influence on the NO release and char combustion processes. The kinetic parameters of NO reduction reaction have no contribution to the conversion time. Under the same particle surface area, the conversion rate of char nitrogen to NO increases with the increase in the particle aspect ratio.