With the increase of power density and lightweight design requirements for internal combustion engine, the interference contact surface of connecting rod big end bearing bush was prone to fretting wear after bearing large alternating load and vibration additional load, which seriously affected the service life and reliability. Based on the connecting rod big end bearing bush of an internal combustion engine, the fretting wear acceleration experiment was carried out under the actual assembly conditions and load characteristics, and the corresponding fretting calculation model was established to study the distribution laws of stress and wear. The results show that the model is in good agreement with the experimental results. The surface stress at the big end of connecting rod body decreases from the middle to both sides under the maximum holding load and in the opposite direction under the maximum tensile load. The fretting wear degree of big end bearing bush is more severe than that of big end cover bearing bush, and the wear degree of edge is more severe than that of center for the bearing bush. In addition, the more severe wear will lead to the greater surface roughness.