Silicon Carbide (SiC) MOSFETs are subjected to complex voltage, current, and thermal stresses under actual operating conditions, which can trigger multi-mechanism coupled chip-packaging aging. Accurately decoupling and character-izing the composite aging characteristics of devices under complex stress is fun-damental to reliability enhancement research. Existing characterization methods only address relatively singular aging mechanisms caused by isolated stresses and cannot characterize the composite aging characteristics of SiC devices under complex stresses. To address this issue, this paper proposes a decoupling charac-terization method for the composite aging characteristics of SiC MOSFETs based on the fusion of dynamic and static multi-features. Through equivalent experi-ments on separated mechanism aging, the multi-mechanism coupling relation-ships between key characteristic parameters such as threshold voltage, on-resistance, body diode voltage drop, and reverse recovery characteristics, and packaging aging, gate oxide aging, and body diode bipolar degradation were un-derstood. A decoupling characterization method for composite aging characteris-tics coupled with multiple aging mechanisms was proposed. Specifically, the gate oxide aging is first evaluated by the threshold voltage shift, then the degree of bi-polar degradation of the body diode is characterized by the percentage change in on-resistance at low current, and finally, the packaging aging of the device is as-sessed by the curve of the percentage change in on-resistance with current at dif-ferent gate voltages or the body diode voltage drop at high current, depending on the situation. This method solves the problem of the inability to standardly evalu-ate composite aging characteristics and provides an aging mechanism evaluation method for the reliability assessment of devices under composite stress. The re-search in this paper is of great significance for promoting the development of SiC power devices in high-reliability applications.