In order to improve the service life of oil film bearing,according to the working principle of the oil film bearing,by using the formula of minimum film thickness of the bearing,the influence factor of the minimum film thickness was analyzed.The settings of the lubrication system components of the finishing mill were introduced,and the contamination control measures of lubrication system were proposed.By controlling the lubricating oil quality through the maintenance of the finishing mill lubrication system to meet the requirements of the oil film bearing on oil temperature,oil pressure,oil cleanliness and oil water content,the service life of the oil film bearing can be extended.Typical accident cases were listed to prove the influence of lubrication system on the service life of the oil film bearing.