Cr-coated zirconium alloy cladding is an important method to improve the high temperature oxidation resistance of light water reactor fuel assembly. The purpose of this paper is to study the high-temperature oxidation behavior of Cr-coated Zr-4 alloys in steam environment. The Cr-coated Zr-4 alloy samples were prepared by multi-arc ion plating process. High temperature oxidation experiments were carried out in 1000 °C and 1100 °C steam environment. The oxidation weight gain of the sample was obtained by a high-precision balance, and the surface and cross-section micro-morphology, element distribution, phase and thickness of the Cr-Zr diffusion layer were analyzed by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray diffractometer (XRD). The results show that there are a large number of droplets of different sizes on the surface of the Cr-coated Zr-4 alloy samples prepared by multi-arc ion plating, and the Cr coating grows preferentially along the (1 1 0) crystal plane. The oxidation weight gain per unit area and time approximately follows a parabolic law. The steam oxidation rate at 1100 °C is significantly higher than that at 1000 °C. At the same temperature, the steam oxidation rate of the Cr-coated Zr-4 alloy is lower than that of the uncoated Zr-4 alloy. After high-temperature steam oxidation, whisker-like oxides were formed on the surface of the samples, and there were a large number of micro-pores between the oxides. After 3 h and 4 h of high temperature steam oxidation at 1100 °C, the surface of the sample was oxidized to form worm-like agglomerates. The cross section of the sample has a layered structure, from the outside to the inside, there are Cr2O3 layer, Cr coating, Cr-Zr diffusion layer, and Zr-4 alloy layer. However, the thickness of the surface Cr2O3 layer does not increase synchronously with the increase of the oxidation time, while the thickness of the Cr-Zr diffusion layer increases with the increase of the oxidation temperature and oxidation time, and has a linear relationship with the oxidation time. Therefore, the Cr-coated Zr-4 alloy prepared by multi-arc ion plating showed good resistance to high temperature steam oxidation at 1000 °C and 1100 °C.