Objective To explore the effect of Kangxian Yixin decoction on PKA/CaMKⅡ Signal Pathway and Mitochondrial membrane potential of cardiomyocyte hypertrophy in dilated cardiomyopathy rats.Methods Drinking furazolidone to duplicate the DCM rats model for 10 weeks,then the rats were checked by ultrasound,the successfully established model rats were randomly divided into model group,low dose Kangxian Yixin decoction group,middle dose Kangxian Yixin decoction group,high dose Kangxian Yixin decoction group and captopril group.Normal group was separated.After 4 weeks of drug intervention,This experiment was over,ATP,Ca2+-Mg2+-ATP enzymatic activity,CaMKⅡ,PKA and UCP2 mRNA were tested.H9c2 cardiomyocyte hypertrophy model was set up by norepinephrine,after 24 h of drug intervention,mitochondrial membrane potential was tested.Results Compared with the normal group,cardiomyocyte mitochondria were damaged in each model group,ATP,Ca2+-Mg2+-ATP enzymatic activity and PKA mRNA were lower,UCP2 mRNA and CaMKⅡ mRNA were higer,mitochondrial membrane potential obviously decreased(P<0.05 or P<0.01).The mitochondria were protected in every drug group,the tested indexes get well in different degree,especially in hige dose Kangxian Yixin decoction group(P<0.05 or P<0.01).Conclusion Kangxian Yixin decoction can reduce myocardial cell mitochondrial damage in model rats with DCM,improve myocardial cell energy metabolism and cardiac systolic and diastolic functions,one of the mechanisms may be optimizing PKA/CaMKⅡ signal pathway and improving mitochondrial membrane potential.