Poor differentiation ability might be the barrier for the stem cell based therapy in ischemic myocardium. Epigenetic regulation play a critical role in this cell fate commitment, however, the mechanisms underlying are largely unknown. To address these issues, we screened for epigenetic regulators of cardiac differentiation using a NKX2.5-GFP mouse embryonic stem cell (mESC) line and found that the chromatin remodeler CHD5 was significantly reduced in mESC derived NKX2.5+ cardiac progenitor cells (CPC) compared with the NKX2.5- population. Deletion of CHD5 in mESC facilitated the CPC differentiation and enhanced the cardiac commitment in vitro. In vivo, we also knockdown CHD5 in c-kit+ CPC and transplant the cells in the ischemic myocardium after MI. The results revealed that sh-CHD5-CPCs improved cardiac function by reducing fibrosis and increasing vascularization. The inhibitory role of CHD5 in cardiac differentiation might be mediated through direct interactions with regulatory regions of cardiogenic genes. Reduced CHD5 expression corresponded with decreased level of the repressive histone mark H3K27me3, and activation of cardiogenic gene expression during cardiac differentiation. Thus, CHD5 acts as a critical epigenetic regulator to cardiac differentiation for stem cells.