Stomach qi refers to the essential qi in the stomach. It is the substantial foundation and energy source of physiological activities such as receiving, storing, and digesting food. Its state can be detected from pulse condition, tongue manifestation, and facial complexion as well as digestive functions. The function of stomach qi falls into two aspects: 1) Digesting and absorbing food and drinks. Stomach qi can promote the gastrointestinal motility, performing preliminary digestion of food and drinks, and moving the resulting chyme downward. This process lays the foundation for further digestion and assimilation. 2) Pulse being moderate and forceful. The presence and strength of stomach qi in the pulse is a crucial indicator of the conditions of disease progress and life vitality. Facial complexion and tongue coating can also mirror the strength of stomach qi.