A prospective multicenter clinical trial was conducted to compare the beneficial effects of a Chinese herbal medicine formula Jiangzhuoqinggan (JZQG) and western antihypertension drug irbesartan. JZQG is mainly composed of rhubarb, coptis, cassia, and uncaria. A total of 240 patients with mild to moderate hypertension were enrolled in the trial. Patients were assigned into two groups after screening: JZQG group and the irbesartan group. After four weeks of treatment, we compared the changes in routine blood pressure, 24 h ambulatory blood pressure, and waist circumference. There was a significant reduction in systolic blood pressure and diastolic blood pressure in the JZQG group (both p < 0.01). There were no significant differences between the reduction of systolic and diastolic blood pressures in the two treatment groups. From the 24 h ambulatory blood pressure measurement, the JZQG group showed a greater reduction in both systolic and diastolic blood pressures (in both daytime and nighttime) than the irbesartan group. Furthermore, there was a significant difference in waist circumference in the JZQG group (1.51 cm reduction; P < 0.05) but not the irbesartan group (0.42 cm). Thus, the JZQG formula may have therapeutic value in patients with both hypertension and metabolic syndrome.