Fresh vegetables → sorting (removing inedible parts) → cleaning → precooking → cooling → cutting into pieces → cleaning → weighing → bagging → sealing → finished products (cold storage). Weighing, bagging and sealing are carried out in a sterile operation room. Instructions: ① Pre-cooking: vegetables: water = 1: 3, add 0.5% citric acid and stir constantly. For tubers and rhizomes, such as carrots and cauliflowers, the pre-cooking temperature is 95 ~ 100℃ and the time is 45 ~ 50 seconds. Celery, garlic bolt, rape and other stem vegetables with more chlorophyll should be pre-cooked at 100℃ for 10 ~ 20 seconds, and water should be added after boiling. Pre-cooking should be thorough, and its flavor, color and texture should be kept as much as possible, especially it should not be soft or coarse fiber-like. (2) cooling: use running water or cold air to cool, and products that are not cooled are easy to change color. ③ Sealing: When sealing, the vacuum degree is close to 0. 1 MPa, and the sealing should be tight and smooth. ④ Control of sterile room: The air is filtered by air filter, and it must be disinfected with ultraviolet lamp for 30 minutes before work. ⑤ finished product preservation: it is better to keep it in the dark at low temperature. (6) The product quality index is still fresh after being stored in the refrigerator for 1 week, with low deterioration degree and good edible quality.