Abstract: This paper takes Xuanyun SW120B aero-engine as the research object.The thermal flow field of the tail is modeled and numerically simulated under the pure gas-phase action and engine deceleration state.By analyzing the characteristics of the tail temperature field and flow field，the distribution and change rule of the engine tail jet flow field and temperature field are derived.A coordinate system is established at the center of the nozzle end face and our results show the temperature and flow rate of the heat flow at the exit of the tail flow is a three-dimensional cone distribution，with the nozzle as the center of the outward diffusion.The fluid is away from the nozzle 0.6 m at the beginning of the tendency to deviate from the center of the axial direction.The high temperature region of the wake stream：z is less than 0.9 m，y is less than 0.5 m，and the temperature range is569～976 K.The low-temperature region：z is more than 2.5 m，y is more than 0.6 m，and the maximum temperature is not more than 323 K.The high-flow velocity region of the wake stream：z is less than 0.2 m，y is less than 0.2 m，and the flow velocity range is 77～100m／s.The low-flow velocity region：z is more than 0.9 m，y is more than 0.2 m，and the highest flow velocity does not exceed 20m／s.The distance of human safety zone：z is more than 2.5m，y is more than 0.5 m.Our research method may provide some references for analyzing the thermal flow field of the wake stream of a large civil aviation engine and dividing safety zone of the ground de-icing operation under the engine jogging.