Abstract:Hydraulic elevator is an important set of equipment in petroleum drilling engineering, which is responsible for tripping action of drill pipe. By understanding the working principle of hydraulic elevator, the possible showing combination of its state was analyzed. Since the life distribution and maintenance time distribution of every composing elements of hydraulic elevator obeying exponential distribution, so its reliability was analyzed by using the Markov model and the Markov state transition model of hydraulic elevator was established according to the principle of Markov process. By using the reliability and maintainability data collected from the hydraulic elevator, the probability of the normal working state was worked out, which was the steadystate availability. At last the weak point of reliability of the hydraulic elevator system is found, which is helpful for the process to improve the hydraulic elevator, and ensuring the safety and stability of drilling process.