The invention discloses a reliability evaluation method of momentum wheel based on multi-performance degradation, which takes performance degradation as a breakthrough point and focuses on the coexistence of multi-degradation processes based on a random process to establish a multi-degradation model based on a Copula function. The key factors affecting the reliability of momentum wheel are analyzed, and the residual lubricant and shafting current are selected as the degradation quantities in the process of performance degradation analysis. The single degradation stochastic process model underdifferent degradation quantities is established, and the failure distribution function form is obtained according to the degradation model. At the same time, the unknown parameters in the degradationmodel are estimated by maximum likelihood estimation, and the single performance degradation model of momentum wheel reliability is obtained. Finally, based on the Copula function theory, the single performance degradation model is used as the edge distribution function, and the joint distribution function of momentum wheel reliability is calculated, and the reliability evaluation process of momentum wheel based on multi-performance degradation is completed.