Abstract:The catwalk is one kind of automated conveyor equipment used in the oil well site to convey drill pipes to the drill floor, and also a kind of complex system driven by hydraulic pressure, among which hydraulic failure is an important reason that may lead to system downtime. By using the catwalk as an example, the operational reliability analysis for complex hydraulic system was done. On the basis of evaluating the structure and working principle of the catwalk, the related reliability block diagram and the reliability evaluation of mathematical models were built up. Through the reliability parameters evaluation and correlation analysis of the hydraulic components, figure out the reliability data of catwalk hydraulic system were figured out. By using the Monte Carlo method to random sampling the catwalk hydraulic system, thereby the accuracy of the reliability calculation method in complex hydraulic system is verified.