The difference between primary and secondary hypertension is interpreted with hypertension as an example. Primary hypertension refers to hypertension caused by heredity or unknown causes. The clinical hypertension often referred to is primary hypertension, which is an age-increasing disease. The incidence increases year by year with age and requires lifelong treatment with antihypertensive drugs. Secondary hypertension is hypertension with a traceable cause, mostly caused by kidney disease, mainly manifesting symptoms of the primary disease, accompanied by elevated blood pressure, requiring symptomatic and etiological treatment in parallel, including drug therapy and surgical treatment. If the primary cause is removed, hypertension is basically cured, and secondary hypertension does not require lifelong use of antihypertensive drugs.