Abstract: The isothermal oxidation behavior of DD6 single crystal superalloys with different interpore matrix sizes at 1050 ℃ was investigated by the static weight gain method. The oxidation products were analyzed by scanning electron microscope, energy spectrum and X-ray diffraction analysis. The results show that the critical size of oxidative damage and thin-wall effect of DD6 single crystal superalloy with gas film pores is 0.75 mm. The electrohydraulic beam machining adopted in this study is an electrochemical corrosion processing method, which makes the electrolytic corrosion layer at the edge of the hole penetrate into the substrate. Thus, the Al₂O₃ film near the innermost layer of the substrate is not completely continuous and dense, which causes the poor protection, and the formation a certain range of high-speed oxidation reaction zone. As the size of the inter-pore matrix increases, the area of the high-speed reaction zone gradually increases to the maximum value and then no longer changes. After that, the effect of growth stress becomes the dominant factor. Tche superposition effect of growth stress gradually decreases with the increase of the inter-pore matrix size, so it shows a downward trend after the peak point.