Abstract: The effects of four different erosion methods on FeCrAl alloy were compared and analyzed by optical microscope and scanning electron microscope. The results show that the grain morphology of FeCrAl alloy could be obviously observed by three chemical erosion methods with 10 g ferric chloride＋30 mL hydrochloric acid＋120 mL distilled water, the volume fraction ratio of HF, HNO₃ and H₂O was 1…10…50, and the volume fraction ratio of HCl and H₂O was 1…3. The thermal erosion method of HCl and H₂O mixed solution was preferred, the microstructure of the alloy obtained by this method had no interference of grain boundary and grain brightness, and the grain size rating photo was clearer. The erosion method of 10 g ferric chloride＋30 mL hydrochloric acid＋120 mL distilled water could be used to observe and analyze the grain boundary. The erosion method with the volume fraction ratio of HF, HNO₃ and H₂O of 1…10…50 could be used for the observation and analysis of the second phase.