The corrosion behavior of high nitrogen austenitic stainless steel in liquid LBE saturated with oxygen at 400 ℃, by different relative flow velocity (0, 0.92, 1.27, 1.61 and 2.01 m/s) for 1000 h was studied by means of SEM with EDS and XRD. The results show that the relative flow velocity may affect the corrosion mechanism of the steel. For static samples, the initial formed oxide scale on the steel surface can effectively prevent further oxidation of high nitrogen steel; for dynamic samples, the initial oxide scale on the steel surface is destroyed, and the coexistence of oxidizing corrosion and dissolving corrosion may occur. When the relative flow velocity increases from 0 to 0.92 m/s, the damage of the initial oxide scale leads to diffusion oxidation of the steel beneath the scale, but the process is mainly oxidizing corrosion; when the relative flow rate increases from 0.92 to 2.01 m/s, alloying elements, which migrate outwards to the surface, will be removed in time at a higher relative flow velocity, thereby the proportion of dissolving corrosion increases, and the oxidizing corrosion decreases gradually. The oxidizing corrosion products composited of oxide particles with double-layered structure, the outer layer is porous Fe₃O₄, and the inner layer is (Fe,Cr)₃O₄.