Abstract: The welded titanium pipe cracked when cold-rolling, and means of chemical compositions analysis, microstructure analysis, fracture morphology observation and energy spectrum analysis were performed to analyze the cracking cause. The results show that the non-standard operations in the welding process made the impurity elements interfuse in the weld which reacted with the oxygen in the air and formed oxycarbide. These oxycarbide became large inclusions in the weld and resulted in local cracking of the welded titanium pipe when cold-rolling.