Abstract: Take sea seed oil, olive oil and palm oil as the main material, the changes of acid value and total polar compounds after frying and essential fatty acids at 180℃ was studied. It was found that acid value significantly increased in three oils with the frying time ( p < 0.05) increase. After frying 20 times, the total polar compounds in three oils ( TPC) increased significantly, the total polar compounds of camellia oil, olive oil and palm oil were16.01%, 20.91% and 17.66% respectively.The final acid value of camellia seed oil, olive oil and palm oil were 0.32, 0.66 and 0.58 mg / g. With increasing number of frying, the frying of three oils saturated fatty acid significantly increased.Unsaturated fatty acids varied widely, C18 ∶ 2, and C18 ∶ 3 was significantly decreased, while C18 ∶ 1decreased gradually.