<p>CF/PEEK is widely used in automobile body and aircraft fuselage manufacturing fields due to its lower processing costs and recyclability. However, due to the influence of collision or environmental factors, microcrack damage such as delamination is prone to occur between material layers in the service process. The large-area delamination in the high stress area must be repaired in time to prevent the damage from continuing to expand and reduce the service life. In this paper, a single-sided ultrasonic welding method for repairing microcracks between interfaces is proposed. Based on the theory of acoustic propagation, the energy transfer model of CF/PEEK single-sided ultrasonic welding interface is established. The optimal process parameters of ultrasonic welding are thus determined by the model and are incorporated into a simulation model, which can accurately simulate the contact behavior and welding characteristics between interfaces during the welding process. The accuracy of the energy transfer model can be further verified by comparing the temperature fields between the experimental and simulation models. The results show that the single-sided ultrasonic welding process parameters designed according to the interface energy transfer model can meet the engineering requirements. The research contents of this study enrich the understanding of the single-sided ultrasonic welding process, and propose a new method for the repair of composite structures.</p>