The present invention provides an adulterated peanut oil detector and an adulterated peanut oil detection method, and pertains to the technical domain of product analysis. The detector comprises a casing, a LCD and Return key, Enter key, Up key, Down key, a power switch, a power socket, and a USB interface arranged on the casing, and a microprocessor and a power supply unit mounted in the casing and electrically connected to the components on the casing, wherein, a module cover is arranged on the top surface of the casing, and a pretreatment module and a detection module are mounted in the space under the module cover. The pretreatment module comprises a heating body and cuvette slots, and the detection module comprises an axial fan, a radiating plate, a refrigerating plate, and cuvette slots. The detection method comprises sample preheating procedure and slow refrigeration procedure. The detector and method provided in the present invention can quickly and easily detect whether the peanut oil sample is adulterated and the percentage of adulteration, and is applicable to quick on-spot detection of rapeseed oil, sunflower oil, maize oil, cotton oil, palm oil, and soybean oil, etc. admixed in peanut oil.