The present invention discloses a preparation method of flavored shredded laminaria japonica. The preparation method consists of the following steps: dried laminaria japonica is washed, the washed dried laminaria japonica is put into a swelling agent which is composed of rice slurry, acetic acids, citric acids and water to conduct swelling, the swollen laminaria japonica is shredded, the shredded laminaria japonica is put into D-sodium erythorbate solution to conduct color protecting; the color protected shredded laminaria japonica is steamed, spices are added, and the mixture is subjected to stir-frying to obtain the flavored shredded laminaria japonica. The spices consists of beef powder, cloves, cortex cinnamomi, dried orange peels, fennel, Chinese prickly ash, pepper, chilies, edible refined salt, garlic powder, disodium inosinate, amomum tsao-ko, yeast, hydrolyzed vegetable proteins, radix angelicae dahuricae, radix astragali, radix angelicae sinensis, C<10>H<12>O<8>N<5>PNa<2>, white granulated sugar, and fresh gingers. The preparation method of the flavored shredded laminaria japonica improves the dried laminaria japonica swelling, laminaria japonica steaming and spice preparing processes according to the processing requirements of the flavored laminaria japonica, so that the processed shredded laminaria japonica products are emerald green in color and luster, fresh, fragrant and chewy in mouthfeel, free of sea smelly smell, and extremely low in nitrite content, and nutrient-rich and healthy food.