Bitter almond contains amygdalin, which can be hydrolyzed by intestinal microbial enzymes or emulsifier contained in bitter almond in vivo to produce trace amounts of hydrocyanic acid and benzaldehyde, which can inhibit respiratory center and achieve the effects of relieving cough and asthma. "Materia Medica Seeking Truth" records that "almonds not only have the function of dispelling cold, but also have the function of relieving asthma". He is good at relieving cough, resolving phlegm and relieving asthma, and has strong pertinence to the main symptoms of lung system such as cough, excessive phlegm and wheezing. Therefore, physicians in ancient and modern times regard it as a medicine for the lung system, and it is often used whenever the lung is involved, regardless of internal injury or exogenous disease. In vitro organ test of guinea pigs, almond water extract can reduce the sensitivity of organs to ammonia stimulation, resist the excitatory effects of histamine, acetylcholine and barium chloride on tracheal smooth muscle, and has obvious cough relieving effect. The cough induced by sulfur dioxide proved that the inhibition rates of amygdalin 1mg/kg, 10mg/kg and 100mg/kg on cough frequency were 26%, 22.8% and 25.3% respectively. The effect of 48.3mg/kg bitter almond extract was 39.7% stronger than that of the same amount of amygdalin. Bitter almond can not only promote the synthesis of pulmonary surfactant (PS), but also improve various physiological and biochemical indexes of lung (such as lung homogenate, lung water capacity, total phospholipids in bronchial lavage fluid and pathological sections).