OBJECTIVE：To in vestigate the effects of quercetin （Que）on the expressio n of angiotensin Ⅱ（AngⅡ）-induced myocardial contractile proteins of primary rats through angiotensin-converting enzyme 2-angiotensin-（1-7）-Mas （ACE2-Ang- （1-7）-Mas）axis. METHODS ：Cardiac tissue of rats aged 1-2 d were collected ，and primary cardiomyocytes were isolated and cultured. The gene silencing model of cardiomyocytes ACE2 was constructed. Experiments were divided into 12 groups. Among them，AngⅡ group，AngⅡ+ small interference RNA （siRNA）group，and Ang Ⅱ+ A 779 group were the model groups ；AngⅡ+ losartan group was positive control group ；AngⅡ+Que40 group，AngⅡ+Que80 group，AngⅡ+siRNA+Que40 group，AngⅡ+ siRNA+Que80 group，AngⅡ+A779+Que40 group and Ang Ⅱ+A779+Que80 group were the experimental groups ；blank group and siRNA group were set up. Ang Ⅱ concentration was 1×10－6 mol/L；siRNA final concentration was 50 nmol/L；Que concentration was 40 and 80 μmol/L；A779（Mas receptor inhibitor ）concentration was 1 μmol/L；losartan concentration was 1×10－4 mol/L. mRNA and protein expression of ACE 2，Ang-（1-7） and Mas in primary cardiomyocytes were detected ；the expressions of myocardial contractile proteins were also determined ，such as Na +/Ca2+ exchange channel （NCX），calcium pump （SERCA2a）， phosphoprotein （PLB）. RESULTS ：Compared with Ang Ⅱ group，mRNA expression of Mas was increased significantly in Ang Ⅱ + Que 80 group （P＜0.05）；mRNA expression of ACE2 and Mas were increased significantly in Ang Ⅱ + CZ0210-01） losartan group （P＜0.05）. Compared with Ang Ⅱ group，the 851136165@qq.com protein expression of ACE 2 and Ang- （1-7） were increased significantly in Ang Ⅱ+ Que 40 group（P＜0.05）；compared with Ang Ⅱ + siRNA group ，the protein expression of Ang-（1-7）were increased significantly in Ang Ⅱ+ siRNA+Que 40 group（P＜0.05）；compared with Ang Ⅱ+A779 group，the protein expression of Ang- （1-7）were increased significantly in Ang Ⅱ+A779+ Que 40 group（P＜0.05）. Compared with Ang Ⅱ group，the protein expression of NCX was decreased in Ang Ⅱ+Que40 group（P＜0.05），protein expression of NCX was reduced in Ang Ⅱ+ losartan group （P＜0.05）；compared with Ang Ⅱ+A779 group，the protein expression of NCX was decreased in Ang Ⅱ+A779+ Que80 group （P＜0.05）. CONCLUSIONS ：Que improves the expression of Ang Ⅱ -induced ACE 2-Ang-（1-7）-Mas axis in cardiomyocyte model to some extent ，so as to regulate myocardial contractile protein.