The reliability of the equipment is very important for the large petrochemical industry,especially for oil pump as the core component of driving equipment. In order to reduce the loss of the enterprise brought by equipment failure,it is need to find those reasons which may lead to equipment failure and take some preventive measures as early as possible. This article analyzes the failure of the oil transfer pump system in CNPC work zone systematically,qualitatively and quantitatively,using the fault tree analysis method. Then 105 groups of minimal cut sets are found,and the probability of system failure after a certain time operation is calculated by using Weibull distribution. Combined with specific requirements of reliability,the work zone may make a scientific decision of plant maintenance cycle according to the conclusion. The reliability of the equipment is very important for the large petrochemical industry, especially for oil pump as the core component of driving equipment. In order to reduce the loss of the enterprise brought by equipment failure, it is needed to find those reasons which may lead to equipment failure and take some preventive measures as early as possible. This article analyzes the failure of the oil transfer pump system in CNPC work zone systematically, qualitatively and quantitatively, using the fault tree analysis method. Then 105 groups of minimal cut sets are found , and the probability of system failure after a certain time operation is calculated by using Weibull distribution. Combined with specific requirements of reliability, the work zone may make a scientific decision of plant maintenance cycle according to the conclusion.