The momentum wheel, as a critical component of the satellite attitude control system, is subjected to disturbances from unknown space orbital environment during operation. Additionally, performance degradation may occur due to wear, fatigue and other reasons, significantly affecting its attitude adjustment capabilities. In view of this, this paper proposed a modeling method for the momentum wheel degradation process based on information geometry. Firstly, a weight fusion method that integrates the Criteria Importance Through Intercriteria Correlation (CRITIC) method and entropy weigh method was employed to determine the weights of various degradation characteristics. Secondly, symmetric and positive-definite matrices were constructed using the degradation characteristic parameters data, enabling the information geometric representation of the degradation process. Subsequently, the current operational state was abstracted as a point on the manifold, quantifying the geodesic distance between this point and a health benchmark point to characterize the degradation level of the momentum wheel. Finally, the efficacy of the proposed degradation model was validated using the Seasonal Decomposition algorithm.