Huan County has a good reputation as "the hometown of minor grains in China". The average elevation of planting on the Loess Plateau is about 1500 meters. The frost-free period is relatively long throughout the year, with strong sunlight and large daily temperature range. It is very suitable for the growth of mung beans. The old mung beans are the local specific characteristics of the old variety "stupid mung beans", which are self-produced, retained and self-made mung beans by the people in Huan County. Due to the difficulty of planting and low yield, they are almost extinct. There are many products called stupid mung beans on the market now, but the real old mung beans are characterized by roundness, luster, deep color, white umbilicus, small size and high germination rate. Real old mung beans are called "green pearls" and contain rich nutrients, including protein, potassium, calcium, magnesium and other trace elements, which are 5% higher than those of ordinary mung beans. It is suitable for summer and cooler to relieve summer heat. Maishangke has its own organic planting base of 20,000 mu, and the planting of the base is in accordance with the requirements of organic planting standards, thus ensuring the safety of coarse cereals.