Black beans are planted everywhere from south to north in China, which is rich in variety resources and ranks first in the world. At present. There are more than 22,000 soybean varieties in China, including 2,980 black beans from China, accounting for 13.2%. Most of them are distributed in the Yellow River valley, which is the main producing area of small black beans. At present, adzuki beans are still mainly planted in the Loess Plateau of northern Shaanxi and Shanxi. In some places, farmers call soybeans black beans, and white beans and black beans black beans, which shows that local black beans are widely planted and have a long history. There are many cultivation types of black beans, most of which are spring black beans cooked once a year in the north; There are both spring black beans and summer black beans in the Yellow River basin. Except spring sowing and summer sowing in Jiangnan. There are also black beans planted in autumn and black beans planted in winter. The growth period of black beans is as short as 90 days and as long as 165 days, so there are varieties with extremely early maturity, early maturity, middle maturity, middle maturity, late maturity and very late maturity. The particle size of black beans is also very different. The smallest, such as black beans in Jixian County, Shanxi Province, weighs only 4 grams. The largest one, such as the black broad bean stem in Jintan City, Jiangsu Province, weighs 3704 grams. Black beans can be divided into micro-grains, small grains, medium grains, medium grains, large grains and extra-large grains, but medium and small grains are the main ones. Black beans have different shapes, mostly rectangular, oblate, oblate, kidney-shaped, and round, with less round particles. The cotyledons of black beans are mostly yellow, accounting for more than 96%, and a few are green, which is called black skin and green kernels. This black bean has high nutritional value and medicinal value. It is called medicinal black bean and is a good variety for export. There are many rare black bean varieties in China. For example, the newly cultivated black beans with bright skin and green kernel in Jiamusi black bean planting base in Heilongjiang Province and the black skin and green kernel in Zhejiang Province are all traditional export products, and their prices are five or six times higher than those of wheat in the international market; The newly cultivated black beans with bright skin and green kernel in Taixing and Jiamusi black bean planting bases in Jiangsu Province are insensitive to light reaction and have strong adaptability, which is extremely rare among various soybean varieties. Small black beans in Yingxian county and Xingxian county of Shanxi province are valuable resources to resist cyst nematode disease. There are many varieties with high medicinal value, and some black bean varieties have special stress resistance and high application value in production and breeding.