At present, the sensor which monitors lubricating oil quality and moisture content on-line based on the change of oil dielectric constant has the problem of temperature compensation for the output value of the sensor. An on-line lubricating oil moisture monitoring sensor with automatic temperature compensation function is studied. The effects of temperature and moisture content in lubricating oil on the response sensitivity and dynamic response stability of the sensor are investigated through experiments. Experimental results show that this type of sensor does not need temperature and other compensation. It has high linear response and sensitivity to the change of moisture in lubricating oil, and can accurately measure the moisture content in lubricating oil, which is stable and reliable.