According to the properties that lubricating oil turns dark after aging,lubricating oil degradation sensing technology based on light absorption was researched to determine the color of the lubricating oil,or directly to detect the degradation state of lubricating oil.According to this principle,an oil color sensor was designed and developed to gather the realtime online lubricating oil color information,and send the data to the database on PC.High temperature lubricating oil aging program was designed,and the aging lubricating oil samples was monitored regularly with laboratory chromaticity and color sensor.The result shows that with the increase of aging time,visual color of lubricating oil is deepening.Through the testing and comparison analysis to the aged oil,the color output and light intensity output of the sensor have strong correlation with the color number tested by instrument in oil lab,indicating that the oil color sensor can be used to detect the color and the degree of degradation of lubricating oils.