Aimed at the problems of force difference of bearing bush and ship shafting vibration caused by different oil film thickness of sliding bearing,taking a bulk cargo ship as the research object,the stress distribution of bearing bush at different oil film thickness was simulated by using the finite element method,and the modal analysis was carried out on the propulsion shafting vibration to obtain the natural vibration frequency and vibration type of the ship shafting.The difference of force of bearing bush and shafting vibration caused by the oil film thickness change was analyzed and compared.Results show that,too small of bearing clearance will cause the deformation of oil film,the oil wedge can not be formed and the oil film cooling effect is reduced,resulting in the increasing of shafting heating and wear.Too large of bearing clearance will reduce the dynamic characteristics of lubricating oil,resulting in unstable shafting operation and more intense vibration of bearing,which is not conducive to the formation of a lubricating oil wedge.The bearing clearance will gradually increase due to the shaft wear,when it exceeds a certain value,the vibration amplitude will be too large to cause a potential danger to the shafting.