Abstract: In order to study the corrosion behavior of China low activation martensitic (CLAM) steel weld bead with TIG welding in flowing lead bismuth eutectic alloy (LBE), corrosion tests of TIG weld bead and base metal of CLAM steel were conducted in LBE with different relative velocity (1.70, 2.31, 2.98 m/s) at 550 °C for 1 500 h. The results indicated that the double-layer oxide layers were observed on the surface of corrosion samples. The outer layer was composed of porous Fe₃O₄, and the inner layer was composed of compact (Fe, Cr)₃O₄. With the increase of the relative velocity of LBE, the dissolution rate of Fe and Cr from CLAM metal matrix into the LBE, the diffusion and migration rate of O from LBE into the CLAM metal matrix were improved, which aggravated the corrosion degree of the samples and finally led to the continuous thickening of oxide layer on the sample surface. Under the same corrosion conditions, the corrosion resistance of CLAM steel weld bead was lower than that of the base metal.