Myocardial ischemia-reperfusion injury (MIRI) is one of the important reasons for the high mortality of ischemic heart disease in patients who have undergone a blood supply reconstruction. Hydrogen sulfide (H2S) has been thought of to be just a toxic gas with a strong odor of rotten eggs for hundreds of years, but it has been demonstrated that H2S plays a protective role in the pathogenesis and development of heart diseases, especially in MIRI. In the present study, we treated rats with H2S after MIRI and then observed its effects on heart function parameters following in situ ischemia/reperfusion. Multiple oxidative products, myeloperoxidase and proinflammatory cytokines in the myocardium were measured to evaluate the anti-oxidative and anti-inflammatory effect of H2S. The role of phosphatase and tensin homologue (PTEN)/PI3K/Akt pathway was examined to explore the underlying mechanism. The treatment of H2S for seven consecutive days exhibited dramatic improvement in cardiac function, as manifested by increased LVSP and +/- (dP/dt) max, and decreased LVDP. PTEN mRNA and expression were decreased by H2S. PI3K/Akt pathway was activated by H2S and PTEN inhibitor bisperoxovanadium (Phen) but de-activated by PI3K inhibitor LY294002. The heart function was enhanced by Phen but worsened by LY294002, suggesting the involvement of PTEN/PI3K/Akt pathway. These results revealed that H2S may exert its cardioprotection by inactivation of PTEN, which in turn activates the PI3K/Akt signaling and increases survival in the MIRI model.