Flaxseed oil is one of the functional oils because of containing 54% ?-linolenic acid that can be used for the production of healthy food. This oil is susceptible to oxidation because of high degree of unsaturation (Iodine index 134-206). The oxidation causes off-flavor and off-odor of flaxseed oil and reduces nutritional value of this oil. In recent years, in order to use of this oil in food products, different methods have been suggested, that one of them is oil encapsulation. One of the encapsulation methods that has recently attracted the attention of researchers is the use complexes between proteins, polysaccharides and polyphenols. In the present study which consisted of 4 stages, possibility of the producing composite aggregates of flaxseed mucilage and gelatin was initially investigated. Then zeta potential, turbidity, fourier transform infrared spectroscopy and complex efficiency at ratios 1:1,1:2, 2:1, 1:3, 3:1(w/w) and pHs 2.5, 3, 3.5, 4, 4.5 were evaluated. By investigation of zeta potential, the result showed that at pH values below 5, gelatin and flaxseed mucilage have positive and negative charges respectively, that allowed the complex formation at pH values below 5. The complex obtained from flaxseed mucilage – gelatin with ratio 1:1 and pH 3 showed maximum amount of turbidity and efficiency. In the second stage, the formation of triple complex of gelatin-flaxseed mucilage- tannic acid oxide was investigated in acidic and alkaline conditions. Total amount of biopolymers was 2% (w/v) and the amount of added tannic acid was 5% concentration of total biopolymers. In this stage, solid state spectroscopy, fourier transform infrared spectroscopy, measurement of efficiency, volume, moisture, solubility and amount of phenolic compounds in the complex were preformed. Finally in this stage, by examination of solid state spectroscopy and fourier transform infrared spectroscopy , it was found adding tannic acid in alkaline pH created the stronger complex. In the third stage, the amount of added tannic acid ( 0.5, 2.5, 5 and 10% of concentration of total biopolymers) and reaction temperature of gelatin and tannic acid (20, 30 and 40°C) were evaluated. In addition to the above analyses, the scanning electron microscope (SEM) and colorimetric assay were performed. It was found, the optimum complex was obtained from 5% tannic acid (concentration of total biopolymers) and at reaction temperature 30°C. In the fourth stage, the possibility of encapsulation of flaxseed oil in triple complex was examined. For this purpose, flaxseed oil in concentration 15, 30 and 50% (w/w) of dry matter of wall was used for preparing the emulsion. After preparing the complex containing oil, by investigation of encapsulation efficiency and loading, 50% flaxseed oil ‌was selected as the best ratio. Supplementary tests such as shape of complex, fourier transform infrared spectroscopy and releasing of oil from complex were preformed. During storage, stability of encapsulated flaxseed oil was determined by measuring peroxide index and thiobarbituric index. The results of FTIR confirmed the presence of flaxseed oil without interaction with functional groups of wall compounds. Finally, oxidative test showed a higher stability of the oil in triple complex. According to the results, this triple complex can be used as wall material for encapsulation of flaxseed oil and improvement of its oxidative stability. Keywords : complex, oxidized Tannic acid, Flaxseed oil, Encapsulation, Oxidative stability