The change of gearbox lubricating oil at present is according to the oil change period provided by the supplier,and there is no tracking,research and analysis of the change of gearbox lubricating oil performance under actual application conditions.In order to accurately determine the reasonable oil change interval of gear box lubricating oil for CRH380B platform electric multiple units（EMUs）of CRH380B platform,the change trend of key indicators of gear box lubricating oil was studied through the physical and chemical properties analysis,the trend analysis of pollutant content and wear element content.The mathematical model of the key indicators changing with the operating mileage of the gearbox lubricating oil was established,and the operating mileage of the gearbox lubricating oil was predicted.The results show that it is feasible to extend the gearbox lubricating oil change interval of CRH380B platform EMUs to 600 000 kilometers.The change of Fe element content can be used as a key monitoring indicator for the extension of the gearbox lubricating oil change interval.According to the mathematical model of Fe element content changing with the operating mileage of the gearbox lubricating oil,it is predicted that CRH380B gearbox lubricating oil still meets the use requirements when operating to 800 000 kilometers.