Abstract: This article discusses common assessment criteria of safety assessment of girth welding joint defects of pipelines. It includes simplified engineering assessment techniques and sophisticated techniques. API 1104 Appendix A, BS 4515 Appendix H and CSA Z184 Appendix K are belong to simplified assessment ways, which are based on COD design curves proposed by Burdiken, and analyzes the acceptance of the defects of welding joint depending on structural plastic collapse analysis. While PD 6493-1991 criteria and CEGB R6 failure assessment criteria are sophisticated techniques. These two sophisticated assessment techniques depend on J integral of structure to assess safety of girth welding joint defects. As to welding joint, the strength match of base material with weld is a key issue. The simplified and sophisticated assessment techniques have their own advantages and disadvantages when dealing with strength mismatch of weld.