Academician Shi Xuemin′s " Qihai theory" and the acupuncture techniques of " Controlling Qihai to regulate blood pressure" have made initial progress in the prevention and treatment of essential hypertension, but the antihypertensive mechanism still lacks further elucidation. After research, there is an important link between Shi′s " Qihai Theory" and the transformation of the phlegm-dampness constitution. With the acupuncture techniques of " Controlling Qihai to regulate blood pressure" , the " high-risk constitution" of hypertensive patients can be changed, or the formation process can be intervened, thus producing a preventive and therapeutic effect on essential hypertension.