There are two categories in terms of major aspects, one is primary hypertension, which accounts for 90-95% of all hypertensive patients; the other is secondary hypertension, which refers to hypertension caused by certain diseases, and hypertension is one of the signs and symptoms of these diseases mentioned above, and secondary hypertension accounts for 5-10% of all hypertensive patients. Secondary hypertensive disorders are distributed among patients with acute, severe, recalcitrant and fluctuating hypertension. In large hospitals, especially in specialist outpatients or inpatients, we counted 91 cases of secondary hypertension among 482 consecutive inpatients, accounting for 20% of all hypertensive inpatients. The main diseases are: primary aldosteronism; Cushing’s syndrome; hyperthyroidism; polyarteritis major; renal artery stenosis; atherosclerotic occlusive disease; pheochromocytoma; pituitary aneurysm; Hashimoto’s thyroiditis; renal parenchymal hypertension; hypertensive syndrome of pregnancy; aortic constriction.