The effects of tanshinone II A on cell signal transduction system protein kinase B in rats with myocardial hypertrophy induced by the abdominal aorta partial coarctation were investigated. Rat models of myocardial hypertrophy were established by using abdominal aorta partial coarctation method. Forty-eight rats were randomly divided into sham group (S group), model group (M group), valsartan treatment group (X group), low-dose tanshinone treatment group (LD group), medium-dose tanshinone treatment group (MD group), and high-dose tanshinone treatment group (HD group) (=8 in each group). Left ventricular mass index (LVMI), left ventricular posterior wall (LVPW), and septal thickness (IVS) were detected by high frequency ultrasonography. Myocardial fiber diameter (MFD) was examined by Hematoxylin-Eosin (HE) staining, and the contents of phosphorylated protein kinase B (p-Akt) and p-Gsk3β in myocardium were assayed by Western blot. The results showed that compared with S group, the values of LVMI, LVPW, IVS and MFD were increased in other groups (<0.05), and the contents of p-Akt, and p-Gsk3β were also increased in other groups. As compared with MD group, the values of LVMI, LVPW, IVS and MFD were decreased in all treatment groups (<0.05), and the contents of p-Akt, and p-Gsk3β were also decreased in all treatment groups. However, there were no significant differences among LD, MD, and HD groups (>0.05), and there were no significant differences between X group and tanshinone treatment groups (>0.05). It was suggested that tanshinone II A could prevent myocardial hypertrophy by its action on the Akt signaling pathway.