Both heart and lung diseases may cause shortness of breath, which can be judged according to accompanying symptoms, underlying diseases, and auxiliary examinations. 1. Accompanying symptoms: heart diseases such as heart failure may cause symptoms of chest tightness and shortness of breath, but they may also be accompanied by lower limb edema, positive hepatic and jugular venous reflux signs, and abnormal heart beats, etc. Lung diseases such as chronic obstructive pulmonary disease (COPD) which may cause symptoms of chest tightness and shortness of breath are often accompanied by chronic cough and white mucous sputum. 2. Underlying diseases: The diagnosis can also be helped by the patient’s underlying diseases, such as previous history of heart failure, sudden chest tightness and shortness of breath after heavy physical labor or infection, the possibility of heart disease; previous history of allergic asthma, sudden chest tightness and shortness of breath after inhalation of suspected allergens, the possibility of lung disease. 3. Auxiliary examination: corresponding auxiliary examination can also be carried out to help diagnosis, such as lung CT and other examinations can be carried out on the lungs, and the heart can be carried out on cardiac ultrasound, coronary angiography and other examinations. It is recommended that patients do not diagnose on their own, but go to a regular hospital, complete the relevant examinations, and follow the doctor’s instructions for treatment.