Objective To explore the mechanism of Xinkang Prescription (Descurainiae Semen Lepidii Semen,Armeniacae Semen Amarum,Poria,Astragali Radix,Citri Reticulatae Pericarpium,Sparanii Rhizoma) for purging the lung and promoting diuresis in treating heart failure by regulating phosphorylation of phospholamban (PLN). Methods Forty-eight C57BL/6J mice were randomly divided into sham-operation group,model group,low-,medium-and high-dose Xinkang Prescription groups(0.455,0.91,1.82 g·kg-1),as well as Entresto group (25 mg·kg-1),with eight mice in each group. The model of ischemic heart failure was established by ligating the left anterior descending coronary artery in mice. After the model was successfully replicated,mice were orally administered with the above-mentioned dosages of Xinkang Prescription and Entresto once a day for four weeks,while sham-operation group and model group were given 0.9％ sodium chloride solution by gavage at the same time. Echocardiography was used to detect the cardiac function of the mice in each group,including left ventricular ejection fraction (LVEF),left ventricular fractional shortening (LVFS),left ventricular end-diastolic dimension (LVEDD) and left ventricular end systolic diameter (LVESD). Hematoxylin-eosin (HE) staining was used to observe the pathological changes in cardiac tissue of mice. qRT-PCR was used to detect the mRNA expression of BNP. Western Blot and Jess were used to detect the expression of PLN,p-Thr17-PLN,p-Ser16-PLN,sarcoplasmic reticulum calcium ATPase 2a (SERCA2a),protein kinase A (PKA),p-PKA,Ca2+/calmodulin-dependent kinaseⅡ(CaMKⅡ) and p-CaMKⅡ in cardiac tissue,and to calculate the ratio of SERCA2a/PLN. The SERCA2a activity was determined by the inorganic phosphorus method.Results Compared with the sham-operation group,the model group showed a significant decrease in LVEF and LVFS(P<0.01) and a significant increase in LVEDD and LVESD (P<0.01). HE staining showed the fibril of cardiac muscle broke and disarranged,accompanied by inflammatory cell infiltration. The mRNA expression of BNP was significantly up-regulated (P<0.01),and the protein expressions of p-Ser16-PLN,p-Thr17-PLN,p-PKA,the ratio of SERCA2a/PLN and SERCA2a activity were significantly down-regulated (P<0.01),while the expression of p-CaMKⅡ was up-regulated (P<0.01). Compared with the model group,LVEF and LVFS in medium-,high-dose Xinkang Prescription groups were significantly increased(P<0.01),while LVEDD and LVESD were significantly decreased (P<0.01). HE staining showed significant improvement in the pathological damage of cardiac tissue. The expression level of BNP was significantly decreased (P<0.01),while the protein expressions of p-Ser16-PLN,p-Thr17-PLN,p-PKA,the ratio of SERCA2a/PLN and SERCA2a activity were significantly increased (P<0.01). The protein expression of p-CaMKⅡ was remarkably decreased(P<0.05). Conclusion Xinkang Prescription can effectively improve cardiac function of mice with heart failure,which may be related to enhance phosphorylation levels of phospholamban.