Flaxseed oil is rich in α-linolenic acid, and its price is 3 to 20 times higher than that of other edible oils, and it is very vulnerable to be adulterated and counterfeited. The authenticity discrimination model of flaxseed oil based on fatty acid (FAs) fingerprints was established. Eight kinds of edible oil samples (flaxseed oil, rapeseed oil, sunflower oil, soybean oil, peanut oil, corn oil, sesame oil, blended oil), two kinds of waste oil samples (kitchen waste oil and gutter oil) were collected, and 12 FAs were determined by gas chromatography. Principal component analysis (PCA) was conducted to observe the clustering properties of these 10 kinds of oils according to their FAs fingerprint. Orthogonal partial least squares discriminant analysis (OPLS-DA) was applied to evaluate the feasibility of FAs fingerprint on authenticity of species origin, processing methods (cold or hot pressing) and grade of flaxseed oil, and partial least squares (PLS) quantitative prediction model was established to estimate the adulteration dosage of rapeseed oil in flaxseed oil. The FAs fingerprint of flaxseed oil was extremely different from other oils. Content of C18:3ω3[(50.14±9.68)g/100g] was significantly higher than that of other oils, while content of C18:1ω9[(16.62±5.02) g/100g] and C18:2ω6[(14.62±4.64)g/100g] were significantly lower than that of other oils. PCA and OPLS-DA both could distinguish species origin, processing methods and grade of flaxseed oil. OPLS-DA had better discrimination formance. PCA and OPLS-DA showed that flaxseed oil was the closest cluster to rapeseed and soybean oil. Accuracy of OPLS-DA for flaxseed oil species discrimination was 100%, accuracy of cold and hot pressing discrimination was 96.7%, and accuracy of grade discrimination was 90.0%. The key FAs for discrimination of flaxseed oil species, processing methods and grade were C18:3ω3, C18:1ω9 and C18:2ω6. Correlation analysis of five key FAs contents in flaxseed oil and adulteration dosage of rapeseed oil showed that C18:3ω3 content was negatively correlated with rapeseed oil adulteration dosage, C18:1ω9 and C18:2ω6 content were positively correlated with rapeseed oil adulteration dosage. R² of PLS quantitative discrimination model for flaxseed oil adulterated with rapeseed oil was 0.986, RMSEE was 4.2635, while RMSEcv was 4.2648, and the prediction error of adulteration dosage was no more than 10%. The results showed that it was feasible to establish the authenticity discrimination model of flaxseed oil by FAs fingerprint, and there was optimization space of this mold.