Aim To observe the anti-apoptosis effect and expression of microRNA-133a （miR-133a） in rat myocardium of heart failure after myocardial infarction （MI）. Methods Sprague-Dawley rats were divided into four groups randomly: ①Sham group: rats were dealt with open-chest ②MI group: rats were operated by left anterior descending coronary artery ligation ③rAAV9 group: rats were operated by left anterior descending coronary artery ligation after transfected with rAAV9-ZsGreen by coronary injection ④miR-133a group: rats were operated by left anterior descending coronary artery ligation after transfected with rAAV9-ZsGreen-pre-miR-133a by coronary injection.Feeding for eight weeks,expressions of miR-133a and mRNA of transgelin-2 （TAGLN2）,Caspase-9 and Bcl-2 were detect by real-time PCR,immunohistochemistry and Western blot were used to determine protein level of TAGLN2,Caspase-9 and Bcl-2. Results The miR-133a expression of MI group decreased obviously compared with sham group （2.963±0.461 vs.12.518±2.21）.The mRNA and protein level of TAGLN2 and Caspase-9 both increased in MI group versus sham group,while Bcl-2 expression decreased in MI group.The expression of miR-133a was up-regulated after rAAV9-ZsGreen-pre-miR-133a coronary injection,the mRNA and protein level of TAGLN2 and Caspase-9 were reduced in the same group,while Bcl-2 expression increased. Conclusions The down-regulation of miR-133a in failure heart after MI could decrease its degradation and inhibiting effects to TAGLN2 and Caspase-9,thus promote myocardial apoptosis.Myocardial apoptosis may be alleviated by over-expressed miR-133a.