The invention discloses a method and a device capable of accurately testing transformer insulating oil furfural content, wherein the method and the device can accurately test the furfural content of transformer insulating oil. The method includes the steps: taking 15 milliliters of transformer insulating oil and 3 milliliters of methanol solution, mixing the insulating oil and the methanol solution in an oscillation manner, filtering mixture, and accurately intercepting 60 micro-liters of extraction solution; pouring 60% of methanol solution and 40% of pure water into a quantitative ring sampler by the aid of a pump, pouring 60 micro-liters of extraction solution into the quantitative ring sampler, beginning to test mixture, and correcting a test result by the aid of an experience coefficient; pumping clear water into a liquid-phase furfural chromatographic column to clean the chromatographic column after testing, and performing testing and cleaning by the aid of same testing containerchannels. Accurate testing data of furfural aging degree of the transformer insulating oil are provided for transformer running fields, and normal running of a transformer is ensured.