Abstract: Fe₂O₃ and CaO are the main metal oxides in coal, which have an effect on NO_x precursor-HCN generation during coal pyrolysis. In order to reveal the mechanism of Fe₂O₃ and CaO on HCN generation during coal pyrolysis, this paper adopts pyrrole as a nitrogen-containing model compound in coal, and investigates the different reaction paths of pyrrole pyrolysis for the generation of HCN, as well as the effects of Fe₂O₃ and CaO on HCN generation under different reaction paths, using the Density Functional Theory (DFT) and molecular simulation means. And Fe₂O₃ and CaO in different reaction paths on the pyrolysis of pyrrole to HCN. The results show that the best path of pyrrole pyrolysis to generate HCN is: H atom migrate from the interval of pyrrole-N to the neighbor, then pyrrole-N is disconnected from the adjacent C, the opening reaction occurs, finally the H atom on pyrrole-N migrate to the adjacent C, C—C bond is disconnected, the transition step of the path is the internal H transfer reaction, compared with the other path, the transition step has the lowest activation energy (2.54 eV). Under the action of Fe₂O₃ and CaO, the pyrrole heat to generate HCN optimal reaction path is: pyrrole-N and neighbor C, open the ring, its H atom migration to the neighbor C, the last pyrrole-N neighbor C and interval, the path of the path is open ring reaction (Fe₂O₃) reaction and internal H transfer reaction (CaO), compared to other path, the path is the lowest activation energy, 3.44 eV (Fe₂O₃) and 1.69 eV (CaO). Under the action of Fe₂O₃, the activation energy of snap steps in different reaction paths increases, that is, Fe₂O₃ inhibited the generation of HCN. CaO shows different effects (inhibition or promotion) on different paths. In the optimal path under the action of CaO, the activation energy of the burst step is reduced to 1.69 eV, that is, CaO catalyzes the generation of HCN. In the same reaction path, CaO is more prominent than Fe₂O₃ in catalytic pyrrole pyrolysis to generate HCN, and HCN forms faster.