Abstract: In order to ensure the underground mining operation can be carried highly,effectively, and safely, always grasp the reliability of hydraulic support, and make the reliability of hydraulic support maintained at a higher level, through the orthogonal test analysis the stress of the key components of hydraulic support under the situation that load at different positions. Research shows that: hydraulic support beams of dangerous section mainly located in the column near the box type structure on the nest, the reliability model can be derived by stress strength interference model . With the increase of load cycles, the reliable degree decreased, when the load cycles increases to a certain value, the material of the top beam to the fatigue limit and failure.