To make maltose with fresh sweet potatoes, fresh sweet potatoes need to be washed first, and the diseased and spoiled parts are removed. Then the sweet potatoes are sliced ​​into filaments using a plundering machine or a boring machine with holes, and they are immediately cooked in pots. There is no hard core in the fresh sweet potato filaments. To cook with the plane. Otherwise, the fresh sweet potato filaments will discolor for a long time. After the fresh sweet potato red silk was cooked, it was placed in a saccharification tank and stirred with water, and the wort squeezed out from the barley malt was added. The barley malt is processed by soaking the barley in cold water for 1-2 hours, until the wheat grain sucks enough water to squash it with your fingers. Unscrew it like an eraser and remove it. Spread on bamboo rafts, 1-2 cm thick. When germination starts, the temperature should be higher. Pour cold water 2-3 times a day. Turn the temperature down and the sprouting length should be 2.5 times that of wheat. The proportion of wort added is 8 kg per 100 kg of fresh sweet potato. After the addition, the saccharification cylinder was tightly capped so that the temperature in the cylinder was maintained at about 55°C. After 8-12 hours, the saccharification process was completed. After the saccharification is complete, the residue is filtered out, put into a pot, boiled and concentrated. Start with firepower and gradually reduce the firepower. To accompany stirring, both accelerate the evaporation of water and prevent coking at the bottom of the pot. When the concentration reaches Baume 36-40 degrees, it can stop the fire, and concentrate the liquid into the container. After cooling, it can be cut into maltose.