Walnuts, also known as walnuts and Qiang peaches, belong to the family Juglandaceae. They are spherical, with a hard shell, yellowish brown on the surface and irregular veins. Walnut prefers light and water, has strong cold resistance, drought resistance and disease resistance, and does not require high soil fertility. Like cashew nuts, walnuts are planted almost all over the world, mainly in Europe, America and Asia, with the highest yield in the United States and China. In China, the famous walnut producing areas include Xinjiang, Shaanxi, Shanxi and Yunnan. Because of its excellent nutritional value, walnuts, almonds (almonds), cashews, and hazelnuts, which are also rich in nutrition, are known as the "four dry fruits".