Objective To analyze the distribution laws of the temperature field and the residual stress field by the thickness, the heating temperature and heating time of the permeability layer. Methods The finite elements software of ANSYS was used to simulate the Fe-Al alloy layer prepared by the hot dipping process. Enthalpy value of aluminum was calculated, and the permeability layer stress was obtained using the indirect coupling method. Results The temperature changes of the alloy layer in the X-axis direction presented a rising trend, with temperature jump phenomenon in some parts. The difference between the highest temperature of the permeability layer (935 . 528 ℃ ) and the heating temperature (950 ℃ ) was 15 ℃ , resulting in a temperature loss of about 1 . 52 % . The temperature showed a downward trend in alloy layers with different thickness, and when the thickness was 200 μm, the decreasing trend of the temperature became smooth without appearance of peaks. With the increase of the coating thickness, the stress first increased and then decreased. Conclusion Considering the effect of the thickness and stress on the properties of the Fe-Al alloy layer, the optimal thickness should be about 200 μm.