Abstract: The anti-impact ability of shafting directly affects the stability and security of a ship's power transmission, and it cannot be ignored that large-scale effects on ships have an influence on the interaction intensity of the impact load. Based on the marine shafting-oil film-stern structure system, the average im-pact load, impact amplitude and orbit of the axle center are analyzed, and the range of shafting speed and load for safe running is determined. The results show that the law of interaction intensity changing with the load is different at different rotation speeds. The interaction intensity of shafting with loads depends on the stern shaft speed and impact intensity, and can be approximated as a function for assessing load carrying ca-pacity.