Abstract: Hazard identification for oil/gas pipeline can find the factors that cause the pipeline fail to realize the weak points, accordingly scientific bases can be provided for accidents causes analysis and preventive measures. Firstly, concepts and processes relative to oil/gas pipeline hazard identification are introduced: also the data needed in pipeline hazard identification and pipeline segment principle are explained briefly. Based on the Fault Tree Analysis (FTA) principles and pipeline accident types, the oil/gas pipeline Fault Tree is framed. Then, Fault Tree is analyzed qualitatively. All the Minimal Cut-Sets (MCS) are calculated by using Fussell-Vesely method and consequently main factors arousing pipeline failure are distinguished. Finally, Fault Tree is analyzed quantitatively. Promoted Expert Judgment Method (PEJM) is put forward to confirm the probabilities of basic events of pipe segments. According to the basic events independence and pertinence respectively, the pipe segment failure probability model, pipeline failure probability model and Probability Importance Index model of basic event are established. The oil/gas pipeline failure FTA is established and analyzed qualitatively. The Top Event is "pipeline failure" and the Sub-Top Events are "leak" and "rupture" in this Fault Tree in which 92 basic events are involved. All the Minimal Cut-Sets (MCS) are calculated by using Fussell-Vesely method. There are 132 MCS in this Fault Tree, including 5 second order MCS and 26 fourth order MCS. Based on the analyzed qualitative analysis result, main causes arousing pipeline failure are distinguished: third destroy, corrosion, pipe material defects and natural disaster etc. Based on the qualitative analysis of oil/gas pipeline failure fault tree, its quantitative analysis is made. Promoted Expert Judgment Method (PEJM) is put forward to confirm the probabilities of basic events of pipe segments and the fuzzy probability is introduced. In this method, experts' option weights are confirmed by Analytic Hierarchy Process method and used to amend experts' options. Finally, according to the basic events independence and pertinence respectively, the pipe segment failure probability model, pipeline failure Probability model and Probability Importance Index model of basic event are established.