Abstract: Modification of whey protein isolate and gum arabic were used as wall material which could form a firm by complex coacervation at the surface of the walnut oil. The microcapsules of walnut oil were immobilized by transglutaminase ( TG- H) . The final products were dehydrated by freeze-drying. The preparation conditions and immobilization conditions were evaluated by the oil-in-rate of microcapsules. The results indicated that the optimum preparation conditions were as follows:walnut oil dosage 0.6mL, modified whey protein isolate 20mL, gum Arabic 6% , pH4.5, stirring speed 300r /min. The optimal immobilization conditions:immobilization pH6.0, the immobilization time of 10h, the immobilization temperature of 10℃, transglutaminase enzyme dosage of 25U /g of gum arabic .The final oil-in-rate could reach 84.15%.In the storage process, the microcapsules could delay walnut oil peroxide value increase.