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Lipase is one of the most useful enzymes in food industry, which can catalyze the hydrolysis and the synthesis of esters. However, the high cost due to the poor operation stability of lipase hinders the wide use of it. In present research, the stability of lipases in aqueous systems has been thoroughly studied, while research on lipases in non-aqueous systems is limited. In this work, the secondary oxidation products of high oleic sunflower oil (HOSO) were determined by HPLC and LC-MS. Formaldehyde, acetaldehyde and hexaldehyde which were confirmed in oxidized oil were selected to test their deactivation effect to two commercial pre-immobilized lipases (Novozym 40086 and lipase DF Amano 15) in non-aqueous system. In addition, the influence of oleic acid and commercial antioxidants (citric acid, tocopherol dl-alpha, tocoblend L70 IP, Tert-Butylhydroquinone (TBHQ) and Rosal-OX LR W/D) on the lipase stability was tested. In order to improve the stability of lipase in the presence of these harmful chemicals, lipase from Rhizomucor miehei was immobilized on MP1000, and the stability of it was tested in the presence of oxidized oil and three detected aldehydes to evaluate the effect of MP1000. The oxidized HOSO and oleic acid were found to cause deactivation of lipases. Citric acid in all concentrations and high concentration of tocoblend L70 IP and tocopherol dl-alpha were found to cause significant deactivation of Novozym 40086 and lipase DF Amano 15. Suitable amount of tocopherol dl-alpha (0.2%), tocoblend L70 IP (0.2%), TBHQ (0.2-1.0 mg/g) and Rosal-OX LR W/D (1.6-3.2 mg/g) would not cause inactivation for Novozym 40086 and lipase DF Amano 15. Lipase RM on MP1000 has better resistance to oxidized oil than that on acrylic resin bead (Novozym 40086)., Lipase is one of the most useful enzymes in food industry, which can be used to produce special fats such as cocoa butter equivalent. However, the high cost due to the poor operation stability of lipase hinders the wide use of it. Oil oxidation is one of the biggest problems in industrial production due to the harmful chemicals produced during oxidation process. Antioxidants, chemicals which usually can prevent oxidation by being oxidized instead of oil, is the most commonly used method in food industry. But the understanding of the effect of antioxidants on lipase stability is limited in present research. In order to solve oil oxidation problem, the compounds of oxidized oil were analyzed with different methods including the analysis of chemical varieties and specific molecule. The evaluation of lipase stability in the presence of oxidized oil compounds and commercial antioxidants was also carried out. In addition, a new carrier (MP 1000) for lipase loading was evaluated whether it can efficiently protect the lipases against oil oxidation. From the results, the oxidized HOSO and oleic acid were found to cause deactivation of lipases. MP 1000 was found to have good resistance to oxidized oil. Citric acid which is a natural antioxidant was found to be harmful to lipases. The other tested antioxidants in unsuitable concentration were also found to be harmful for lipases. The effect of different antioxidants on different commercial immobilized lipases obtained in this work can be used as reference for company when choosing the antioxidants and deciding the amount to use. Based on the confirmation of harmful chemicals for lipases in oxidized oil, pretreatment of oil to remove these chemicals could be developed. From the results, MP 1000 seems to be a better carrier for lipases compared with present used carriers. This could be a direction in lipase immobilization research. During the work, ethanol was found to have positive effect on lipase stability which is on the con