This study utilizes both experimental and numerical methods to investigate the fretting fatigue failure of TC4-carbon fiber reinforced plastic (CFRP) riveted single-shear lap joints under varying CFRP thicknesses and cyclic loads. It focuses on analyzing the dynamic response, the evolution of the contact state, and the failure mechanisms of these joints. Findings indicate that the fatigue testing process consists of two distinct stages. In the partial slip state under low loads, the interfacial temperature remains at approximately 30°C, and fretting fatigue failure initiates on the CFRP surface. During the gross slip state under high loads, the interfacial temperature rises to around 58°C, and the combined effects of carbon fiber structural damage and matrix bond breakage result in macroscopic wear of the CFRP. Increasing the thickness of CFRP significantly prolongs its fatigue life. For the same load half-amplitude, the fatigue life is extended by approximately 2000 times. Therefore, enhancing fatigue performance at low loads is achievable by modifying the thickness, but high loads necessitate the use of high-temperature-resistant composite materials.