In order to explore the effects of different edible oils and fried foods on the formation of trans fatty acids， five varieties of edible oils （sunflower oil， soybean oil， rapeseed oil， palm oil and peanut oil） were used to fry 14 batches of fritters at a certain temperature. The fritters， in turn， use soy-fried tofu， fritters and chicken legs to analyze the frying oil produced in both cases by gas chromatography to compare the trans fatty acid content. The results showed that the content of trans fatty acids in edible oil increased with the extension of frying time. The total content of trans linoleic acid in sunflower oil was the highest， reaching about 12 mg/g， and the trans oleic acid was lowest in peanut oil， about 0.6 mg/g. The content of trans fatty acids in soybean oil did not change significantly during the frying process， and remained at about 3.5 mg/g. It can be seen that the trans fatty acids produced by different types of edible oils have a large difference in heating process. When using soybean oil to fry tofu， fritters and chicken legs respectively， there is no significant difference in frying oil trans fatty acids. Indicating the frying process， the trans fatty acids are mainly derived from the oxidative cleavage and isomerization of unsaturated fatty acids in edible oils， and have little to do with frying materials. From the perspective of the formation of trans fatty acids， it is recommended to use soybean oil for long-term frying in cooking， and it is not suitable to use sunflower oil.