In view of the small failure sample in the equipment life test, a quantitative analysis method for equipment system reliability evaluation based on impact stress is presented. Firstly, graphic evaluation and review technique （GERT）is introduced to describe the multiple working states of the system and transitive relations between the states. And a reliability evaluation model is constructed based on the system structure. Then the reliability of the components is estimated according to observed failure data, and the parameters in the reliability GERT network are determined. Finally, the system reliability is evaluated according to the network computing results. Case study results show that the equipment reliability GERT model is effective. 