Old duck soup should be eaten in summer. Due to the hot and rainy climate in summer, summer dampness often makes people trapped in the spleen and stomach and lose appetite. Therefore, it is necessary to use diet to adjust and supplement, increase the intake of nutrients, and achieve the purpose of eliminating summer heat and fatigue. Nutrients should be light and nourishing food, that is, "clear". Old duck is a good tonic in summer. It is not only nutritious, but also very cold because it lives in water all the year round. It has the effects of nourishing the yang of the five internal organs, clearing away the heat of fatigue, nourishing blood and promoting blood circulation, nourishing the stomach and promoting fluid production.