Abstract: The pulmonary artery hypertension occurs within (5～10) min while human enters the hypoxic environment, which is the normal physiological response of the body to hypoxia. However, the degree of pulmonary artery hypertension is not only one of the important indicators of the body adaptation to acute hypoxia, but also an early warning indicator to judge whether high altitude pulmonary edema occurs. During the long-term stay at high altitude, pulmonary artery hypertension may be used as an objective basis for studying and judging the reasonable residence duration, as well as analyzing the adaptability of the body to chronic high altitude hypoxia. The irreversible remodeling of pulmonary circulation vessels and severe right ventricular hypertrophy caused by long-term pulmonary artery hypertension are the signs of transformation to chronic high altitude disease.