Abstract: External interference, construction defect, material failure, corrosion, and ground movement are the initial causes that bring on the failure of transmission pipeline. The reliability of transmission pipeline system lies on the failure probability. The effect of failure was described by the fault serious degree. Appling the theory of fuzzy integrated judgment to analyse the fault serious degree, it can be divided into fatal, severe, generic and light etc. The failure probability, effects on the reliability of pipeline system, the cost of maintain composes the factor classes, there are some different factors in each factor class. Many influencing factors of pipeline's failure were considered in the fuzzy integrated judgment, and it avoided the disadvantage of judgment result, which only used the failure probability to evaluate the fault serious degree of transmission pipeline.

Key words: transmission pipeline, failure, fuzzy mathematics, integrated judgment