FeCrAl / ZrNbCu dual layer tube is one of the candidate materials for accident tolerant fuel cladding, which takes the advantages of ZrNbCu alloy and FeCrAl alloy into account. In this paper, the high-temperature steam oxidation behavior of FeCrAl /ZrNbCu dual layer tube is studied. The results show that the outer layer FeCrAl material has excellent high temperature steam oxidation resistance, and the inner ZrNbCu alloy layer can be effectively protected by FeCrAl alloy. The concave and convex morphology of oxide film of FeCrAl alloy is formed, and the oxidation products are Fe2O3, FeCr2O4, Cr2O3 and Al2O3. The oxide film of ZrNbCu alloy grows perpendicular to the surface, and the oxidation products are ZrO2 and Nb2O5. Element diffusion at the interface of the dual layer tube can not be found when it is oxidized at 1000 ℃; there is obvious element diffusion at the interface when it is oxidized at 1100 ℃ and 1200 ℃. From the outer side to the inner side of the dual layer tube, FeCrAl oxide film, FeCrAl alloy, FeCrAl-ZrNbCu diffusion layer, ZrNbCu alloy and ZrNbCu oxide film are formed; the original mechanical bonding transforms to metallurgical bonding when the temperature is above 1100 ℃.