Oil acidity value is an intelligent sensor for online measurement of changes in oil acidity. By using impedance spectroscopy measurement technology, the acid value index of oil products can be continuously monitored in real-time online. Electrochemical Impedance Spectroscopy (EIS) is a high-frequency detection method that studies the characteristics of electrochemical systems by applying a small alternating current signal and measuring the system response. This method has ultra-high accuracy (leading by 2 orders of magnitude in dielectric constant). The traditional dielectric constant method only measures capacitance changes at a single frequency and is susceptible to temperature and impurity interference. EIS captures multi-scale information such as dielectric relaxation and ion migration through broadband scanning (such as 1kHz~100kHz), combined with equivalent circuit separation of polarization resistance (acid value related) and solution resistance (resistivity related), with an accuracy of up to 0.1%.