To avoid worsening the consequences of oil and gas pipeline accidents due to emergency failures，the causes of emergency failure in 27 accidents at home and abroad were analyzed using the HFACS model. Based on the results of grounded theory (GT) statistical coding analysis，a classification model of failure causes of emergency response in oil and gas pipeline accidents was proposed. SNA was used to develop the relationship network of the causes of emergency failures in oil and gas pipeline accidents. The core-periphery，centrality，and association direction index analyses were used to identify core factors and factors with high association and strong mediating roles in the classification model of the causes of emergency failures in oil and gas pipeline accidents. The results indicated that the classification model of emergency failure causes in oil and gas pipeline accidents was divided into five levels: government and emergency department factors，operator organizational factors，operator unsafe supervision，preconditions for unsafe behavior of on-site personnel，and unsafe behavior of on-site personnel. The emergency failure causes were further divided into 16 bottom-level factors，among which there were 9 core factors: inadequate safety supervision by government and emergency departments，ineffective emergency rescue，regulations defects，insufficient supervision by pipeline operators，technical environment，and skill errors. Skill errors，regulations or procedure defects，technical environment，and insufficient supervision by operators were highly associated factors. Moreover，pipeline operators' regulation defects，procedure defects，technical environment，insufficient supervision，improper resource management，and decision-making errors were strong mediating factors.