Abstract: The corrosion of liquid lead-bismuth is the main problem that restricts the development and practical application of lead-cooled fast reactor (LFR), commercial 9%-12% Cr ferrite/martensite steel (F/M) has excellent high temperature mechanical properties and is considered the preferred structural material in LFR. This paper studied the corrosion behavior of 10Cr9Si1Mo1VNb steel at 450 ℃ static saturated oxygen liquid lead-bismuth eutectic (LBE), for 9% Cr heat-resistant steel in the LFR nuclear system to provide a certain data support and theoretical reference. X-ray diffraction (XRD), scanning electron microscope (SEM), electron probe microanalysis (EPMA) methods were used. The microstructure and composition of 500, 1 500, 3 000 and 4 500 h samples were analyzed. The oxide film thickness of each layer was measured and the mechanism of oxide film growth was discussed. Based on the experimental results of 10Cr9Si1Mo1VNb steel, the oxidation model of steel in 450 ℃ static saturated oxygen liquid LBE was proposed. The results show that 10Cr9Si1Mo1VNb steel is exposed to LBE, and test steel corrosion forms mainly with oxidation corrosion. The surface of the test steel forms a three-layer oxidation film, consisting of outer oxide layer, sub-outer layer and internal oxidation zone (IOZ). As can be seen from the EDS analysis, the outer oxide layer is mainly Fe₃O₄. The sub-outer layer consists mainly of Fe-Cr spine and SiO₂. The outer oxide layer structure is loose, Pb can penetrate inward through the outer oxide layer. The sub-outer structure is dense and Pb-Bi intrusion is largely non-existent. The IOZ is characterized by the presence of the oxidation reaction at the crystal boundary, where the inward diffusion of oxygen combines with Cr and Si. The priority oxidation occurs at the crystal boundary, and the formation of rich Cr and rich Si oxides occupy the crystal boundary. After statistics and comparison of 500-4 500 h test steel oxide film thickness changes, it can be observed that the outer layer of 500-4 500 h is in a growth trend. There is a small increase in the thickness of the 500-4 500 h outer oxide layer. After 1 500 h the IOZ thickness begins to decrease gradually. The experimental results show that 10Cr9Si1Mo1VNb steel forms a three-layer oxidation film in LBE, consisting of outer oxide layer Fe₃O₄, sub-outer layer Fe-Cr spine and SiO₂ and IOZ. The combination of Si in the substrate with the inward diffusion oxygen forms SiO₂ in the IOZ and the sub-outer layer, promoting the formation of rich Cr oxides. Si and Cr show synergistic effect, can effectively improve the oxidation resistance of steel and lead-bismuth corrosion resistance. The test steel corrosion early oxidation rate is faster, after corrosion 1 500 h the oxidation film thickness growth rate slows, and sample surface forms a continuous dense spar layer, can effectively impede the diffusion of elements and slow down the oxidation rate.