Abstract: The cracked cold bending specimens of 15MnVN_q(C、B) steel butt welded joint were analyzed with SEM technology, energy spectrum, metalographic examination, and the detection of residual hydrogen content. The removal of hydrogen from the test piece was also done to study the cause of cracking in cold bending specimens. It was proposed that the internal factor to cause the formation of crack near the surface of cold bending specimens is the presence of stripped/flaked inclusions in the base metal, the external factor is the accumulation of hydrogen around the inclusions caused by various factors. The crack is one kind of internal hydrogen embrittlcmcnt, and may be avoided by the reduction of the amount and characteristics of inclusions through further improvement of metallurgical processes.