The invention discloses a compensation method for online measurement of the amount of lubricating oil. The compensation method for online measurement of the amount of lubricating oil includes the following steps: step 1: collecting a dielectric constant compensation capacitor UK and an output signal U of an effective measuring portion by a sensor; step 2: acquiring a dielectric constant of the lubricating oil in a fuel tank; and step 3: obtaining an oil immersion height voltage signal UH of the senor through parameters in the step 1 and the step 2. According to the compensation method for online measurement of the amount of lubricating oil, changes of the dielectric constant of the lubricating oil medium caused by changes of the temperature and the quality of the lubricating oil can be measured, change signals of the dielectric constant are output to a signal conversion part to achieve the compensation of the whole sensor for changes of the dielectric constant of the lubricating oil caused by temperature changes, and the oil quantity of the lubricating oil is accurately measured.