The effect of Hf on high-temperature oxidation behavior of K4800 nickel-based superalloy was studied. The results show that the oxidation kinetics curves of K4800 and K4800+0.25Hf alloys obey parabolic law during thermostatical static oxidation at 800 and 850 ℃.However, the initial static oxidation rate of K4800+0.25Hf alloy (0.026 g/m²·h at 800 °C for 20 h and 0.061 g/m²·h at 850 °C for 20 h) is lower than that of K4800 alloy (0.041 g/m²·h at 800 °C for 20 h and 0.066 g/m²·h at 850 °C for 20 h). The oxide layer of the two experimental alloys consists of outer oxide layer and an inner oxide layer. The outer oxide layer primarily consists of dense Cr₂O₃, while the inner oxide layer mainly contains dendritic Al₂O₃. However, with the increase in Hf content from 0wt% to 0.25wt%, the thickness of the Cr₂O₃ outer oxide layer decreases from 2.71 μm to 2.17 μm after oxidation at 800 °C for 1000 h and from 5.83 μm to 4.09 μm after oxidation at 850 °C for 1000 h. The results of EPMA analysis indicate the formation of HfO₂ at the grain boundary of the oxide layer in the K4800+0.25Hf alloy, promoting the formation of Al₂O₃ around HfO₂ and accelerating the growth of Al₂O₃. The presence of Al₂O₃ and HfO₂ at the grain boundary contributes to the reduction of the outward diffusion rate of Cr³⁺ and the delaying of thickening of the Cr₂O₃ oxide layer. Consequently, the trace addition of Hf enhances the oxidation resistance of the K4800 alloy.