Abstract：Objectives：To observe the clinical effect of Xiakucao tang combined with valsartan on essential hypertension and its effect on vasoactive substances. Methods：A total of 87 cases of patients with essential hypertension were randomly divided into the control group and the study group，43 and 44 cases in each group respectively. The control group was treated with valsartan， and the study group was treated with valsartan combined with Xiakucao tang. The levels of 24 h dynamic monitoring of blood pressure，blood lipid changes，vascular endothelial function and overall clinical effects in the two groups were compared. Results： The total effective rate was 97.7% in the study group and 81.4% in the control group， the difference being significant(P＜0.05). Before treatment，there was no significant difference being found in the comparisons of the mean levels of daily systolic blood pressure(dSBP)， daily diastolic blood pressure(dDBP)， night- time systolic blood pressure(nSBP)， night- time mean diastolic blood pressure(nDBP)， 24 h mean systolic blood pressure(24 hSBP) and 24 h mean diastolic blood pressure(24 hDBP) between the two groups(P＞0.05). At 8 and 16 weeks after treatment， the mean levels of dSBP，dDBP，nSBP，nDBP，24 hSBP and 24 hDBP in the two groups were decreased when compared with those before treatment(P＜0.05)，and the decrease in the study group was more significant than that in the control group(P＜0.05). Before treatment， there was no significant difference being found in the comparison of levels of total cholesterol(TC)， triglycerides(TG)， low- density lipoprotein- cholesterol(LDL- C) and high- density lipoprotein- cholesterol(HDL- C) between the two groups(P＞0.05). After treatment，TC，TG and LDL-C in the two groups were decreased when compared with those before treatment(P＜0.05)， and HDL- C was increased(P＜0.05)； the improvement of each index in the study group was more significant than that in the control group(P＜0.05). Before treatment，there was no significant difference being found in the comparison of levels of Nitric oxide(NO)，endothelin- 1(ET- 1)，endothelial nitric oxide synthase(eNOS) and prostacyclin (PGI-2) between the two groups(P＞0.05). At 8 and 16 weeks after treatment，the levels of NO，eNOS and PGI-2 in the two groups were increased when compared with those before treatment(P＜0.05)，and level of ET- 1 was decreased(P＜0.05)； the improvement of each index in the study group was more significant than that in the control group(P＜0.05). Conclusion： Xiakucao tang combined with valsartan for essential hypertension has a significant curative effect，and can improve blood lipid levels and effectively regulate vasoactive substances.