Objective To explore the possible mechanism of action of Liqi Huatan Huoxue Formula（ 理气化痰活血方） in improving coronary microcirculation disturbance. Methods A total of 245 healthy male SD rats were randomly divided into a Liqi Huatan Huoxue Formula group

a valsartan group and a model group

with 80 rats in each group. In addition

a blank group was set with 5 rats. Except for the blank group

the other 3 groups were established a model of coronary microcirculation disorder by injecting sodium laurate into the left ventricle. The Liqi Huatan Huoxue Formula group and the valsartan group were given Liqi Huatan Huoxue Formula（ concentration 2. 25 g/ml）and valsartan suspension（ concentration 8. 89 mg/ml） 1 ml/100 g 1 day before operation and 4 weeks after operation.The model group and the blank group were given 1 ml/100 g of distilled water for gavage

once a day. During the experiment

the deaths of the rats in each group were observed. Five rats were randomly sacrificed at the time points of1 h

24 h

1 w

2 w

3 w and 4 w after the operation in the Liqi Huatan Huoxue Formula group

the valsartan group and the model group. The rats were sacrificed at 4 w in the blank group. The concentrations of serum endothelin-1（ ET-1）

nitric oxide（ NO）

von Willebrand factor（ v WF） and myocardial tissue fibrin（ fgl 2） mRNA were detected.Results There were 44 deaths

40 deaths

and 42 deaths respectively in the model group

Liqi Huatan Huoxue Formula group and the valsartan group. There was no statistically significant difference in the intraoperative and postoperative mortality among the 3 groups（ P > 0. 05）. At 4 w after operation

the concentration of serum ET-1 in the model group was higher than that in the blank group

and the concentration of vWF was decreased（ P < 0. 01）. There was no significant difference in serum NO concentration and fgl 2 mRNA expression between the 2 groups（ P >0. 05）. At the same time

compared with the model group

the serum ET-1 concentrations in the Liqi Huatan Huoxue Formula group and the valsartan group were decreased at 1 h

24 h

1 w

2 w

3 w

4 w（ P < 0. 05 or P < 0. 01）.Compared with the model group and the valsartan group

the serum NO concentration increased and the vWF concentration decreased（ P < 0. 05 or P < 0. 01）. The expression of fgl 2 mRNA in myocardial tissue at 2 w

3 w in the Liqi Huatan Huoxue Formula group was significantly lower than that of the model group（ P < 0. 01）. Conclusion Liqi Huatan Huoxue Formula may protect vascular endothelial function by reducing the concentration of ET-1 and vWF in serum and the expression of fgl 2 in myocardial tissue and increasing the concentration of NO in serum of rats with coronary microcirculation disturbance.