Several pipeline girth-weld fracture and explosion accidents recently posed a challenge to the safety of high-strength steel pipelines. Failure analysis reports of cracking girth-welds from in-service X70/X80 pipelines are summarized to identify the patterns and main factors influencing girth-weld crack formation. Statistical analysis was conducted first from the aspects of crack initiation, size, and mechanical properties of girth-weld with cracks or other types of welding defects. Most cracks initiate from the toe of the weld at the top and bottom of the girth-weld and propagate in the thickness direction. Crack tip opening displacement (CTOD) and cross-joint specimens were tested to study the influence of strength under-matching and fracture toughness on girth-weld cracking. For these girth-welds containing crack defects, an obvious tendency of strength under-matching and lower fracture toughness was observed, significantly influencing the failure mode transition. The statistic and experimental results of present girth-weld cracking failure analysis will benefit mechanism analysis and prevention of girth-weld cracking failure.