The invention discloses a method for detecting the quality of edible oil by detection of the density of objects based on a magnetic suspension technique, and belongs to the technical field of magneticsuspension detection. The detection method comprises the steps: (1) preparing a mixed oil of a sesame oil and a peanut oil, and selecting soybean oils with different high-temperature heating time length; (2) preparing an appropriate paramagnetic medium solution; (3) dropping sample oil droplets into the paramagnetic medium solution; (4) placing the solution in a magnetic suspension detection device; (5) measuring the suspension height of the oil droplets; and (6) according to the properties of the oil droplets and the corresponding suspension height, obtaining the relation between the accounting ratio of the sesame oil in the mixed oil and the suspension height, and the relation between the different time length of the high-temperature heated soybean oils and the suspension height, wherein the relations are used for analyzing the quality of the edible oil. The invention provides the brand-new and simple method for detecting the quality of the edible oil; the method can do qualitativeand quantitative analysis of adulterated oil in the sesame oil, and can also detect and analyze the quality of soybean oils used for deep-fried food and obtained after deep frying.