Abstract: Conventional nitrogen injection in longwall gob often fails to achieve the expected fire prevention effect due to its poor cooling effect. Therefore, a technical scheme for preventing spontaneous combustion of coal in gob by cooling nitrogen injection and a corresponding deep cooling equipment system were proposed, and a multi-physical coupling model for spontaneous combustion of coal in gob was simulated to make it suitable for nitrogen injection. The results show that cooling nitrogen into the goaf can significantly reduce the temperature of the high temperature area by about 5 ℃, and effectively reduce the risk of spontaneous combustion of coal in the goaf. The simulation results of nitrogen injection agree well with the field data, which verifies the accuracy of the nitrogen injection model. There is an optimal position of nitrogen injection point in the gob, which can inhibit coal spontaneous combustion to the greatest extent.