Objective To observe the effect of Kangxian Yixin Formula（Formula for relieving fibrosis and tonifying the heart） on the expression of myocardial matrix metalloproteinase-1（MMP-1） and tissue inhibitor of metalloproteinase-1（TIMP-1）.Methods One hundred Wistar male rats were randomized into normal group

10 rats

and model group

90 rats.The dilated cardiomyopathy models were established by raising with furazolidone solution for 8 weeks.Then 70 successfully made models were randomized into 5 groups

i.e.model group

captopril group

Kangxian Yixin Formula high-dose and low-dose groups

and integrated Chinese and western medicine group

with 14 in each.The models were given normal saline

captopril 10.125mg/kg

Kangxian Yixin Formula 18.8g/kg or 4.7 g/kg

and the mixture of Kangxian Yixin Formula high-dose and captopril respectively as intervention for 8 weeks.Six rats of each group randomly selected were treated with immunohistochemical staining for measuring the expressions of MMP-1 and TIMP-1.Results Compared with the model group

the MMP-1 expression in the integrated Chinese and western medicine group

Kangxian Yixin Formula high-dose group

and captopril group was significantly down-regulated（P<0.05）

the TIMP-1 expression up-regulated（P<0.05）.MMP-1 expression in the Kangxian Yixin Formula low-dose group was down-regulated（P<0.05）

while its TIMP-1 expression was not different from that in the model group（P>0.05）.Conclusion Kangxian Yixin Formula could effectively down-regulating MMP-1 expression and up-regulating TIMP-1 expression.This may be one of its functional mechanisms in inhibiting the remodeling of ventricle of heart through relieving the myocardial fibrosis of dilated cardiomyopathy heart failure rats.