The invention relates to a processing method of brassica napiformis. The processing method specifically comprises the following steps: (1) selecting mature brassica napiformis having no disease and pests, removing soil on the brassica napiformis, cutting leaves and roots, clearing fluff on the brassica napiformis by using a brush-type tool, washing in washing liquid, draining in a fresh-keeping storehouse, keeping the temperature in the fresh-keeping storehouse at 6 to 10 DEG C, and keeping the relative humidity at 75 to 78 percent; (2) taking out the brassica napiformis from the fresh-keeping storehouse, shredding the brassica napiformis, wherein the shredding adopts manual shredding or mechanical shredding, and shredding in a vacuum environment or in water, so as to prevent the brassica napiformis from contacting the air; (3) blanching the brassica napiformis shreds in water of 85 DEG C or higher for 5 to 20 seconds, taking out the brassica napiformis shreds, cooling, mixing the cooled brassica napiformis shreds and raw peanut or dried fish according to a mass ratio of 1 to (0.3 to 0.5), canning, then adding water which is 2 to 3 times of the weight of the brassica napiformis shreds and the peanuts, and sealing for 3 to 5 days; and (4) opening, taking out the brassica napiformis shreds and the peanuts, and mixing the brassica napiformis shreds and seasoning for eating. The peanuts are used for extracting brassica juncea oil.