Objective： Due to the blackness of sensitivity, selectivity and fatty acid quantification of traditional methods, a new method for determining fatty acids in vegetable oils without derivation was developed. Methods: The content and types of fatty acids in vegetable oil were analyzed more accurately by high-performance liquid chromatography combined with evaporative light scattering detector, CNW^ C₁₈-WP column (4.6 mm×250 mm, 5 μm) was used. Mobile phase A was 0.1% formic acid aqueous solution, and mobile phase B was 0.1% formic acid methanol solution, using gradient elution at the flow rate of 1.0 mL/min; the temperature of the column temperature box was set at 25 ℃, and the injection volume was 30 L. Drift tube temperature of evaporative light detector was 75 ℃, and the oil-free air pump provides carrier gas was at a flow rate of 2.0 L/min. The gain was set at 4. Results: The results showed that tetradecanoic acid, palmitic acid, linolenic acid, oleic acid, stearic acid, arachidonic acid, erucic acid and henyl acid had a good linear relationship, high stability (RSD＜3%) and good precision (RSD＜3%). The minimum detection limit of erucic acid was 10^-3 mmol/L, and the minimum detection limit of other fatty acids was 10^-2 mmol/L under that method. The recovery rate met the experimental requirements (the average recovery rate of each fatty acid was 90% to 110%). Conclusion: This method has good linearity, high stability and precision. In conclusion, this method is suitable for determining of the nine kinds of fatty acids in vegetable oil.