2,6-Di-tert-butyl-4-methylphenol (BHT), also known as 2,6-di-tert-butyl-p-cresol (DBPC), is an antioxidant widely used in transformer oil. The electrochemcial properties of BHT in transformer oil were investigated by using electrochemical techniques, and a new determination method of BHT in transformer oil based on differential pulse voltammetry was established. It was confirmed that the intensity of characteristic peak of differential pulse voltammetric corresponded for BHT exhibited a good linear relationship with the concentration of BHT within the concentration range from 0.01 to 0.5 %. After researching the accuracy of the experimental results by using spectrophotometry, liquid chromatography, and the electrochemical method, it was further demonstrated that the electrochemical method could be applied to the determination of the content of BHT antioxidant in transformer oils.