Abstract: A lot of intricate information in momentum wheel's ground test has been accumulated.However,an effective method for reliability analysis by fusing such information can hardly be found.The paper firstly proposed a method to build the reliability model of momentum wheel by fusing various test information and expert knowledge using Bayesian network.Then,the reliability assessment,fault diagnosis and sensitivity analysis towards momentum wheel's ground test were carried out using the inference of Bayesian network.The proposed method could solve the problem of reliability analysis and assessment of momentum wheel's ground test,providing a theoretic guidance for reliability test of momentum wheel.