Presently, there are no conventional treatments for cardiac stress injury, and the existing therapies are not always effective. Estrogen(E2) plays an important cardioprotective effect when β-adrenergic receptors (β-ARs) were over stimulated by catecholamine storm. The lately discovered estrogen receptor GPR30 executes rapid effects of E2. In this study, we investigated GPR30 effect on myocardium and analyzed its mechanism in stress state. Stress model was developed by epinephrine (Epi) both in vivo(8.56×10-8mol/100g) and in vitro(100nM/L) in rat and human induced pluripotent stem cells-derived cardiomyocytes (hiPSC-CM) (Paur et al. 2012). G1 (48μg/100g) or G15 (76μg/100g) were used as agonist or antagonist of GPR30(Cao et al. 2015) . Values are means ± S.E.M., compared by one-way ANOVA followed by Bonferroni post hoc tests. (1) In stress state, GPR30 activation with G1 improved heart function by decreasing LVIDs (G1+Epi: 1.92±0.20 vs. 3.80±0.04 mm Epi treated, P<0.01 ,n=4) and increasing the EF% ( G1+Epi: 92.46±2.41 vs. 73.22±1.63 % Epi treated, P<0.01, n=4) measured by echocardiography, and increasing cardiomyocyte contraction amplitude (G1+Epi: 10.50±0.86 vs. 7.86±1.09 % Epi treated, P<0.01, n=10). It also decreased LDH (G1+Epi: 651.20±20.60 vs. 858.60±27.18 U/L Epi treated, P<0.01,n=3) and BNP (G1+Epi: 73.41±1.96 vs. 90.50±2.10 μg/L Epi treated, P<0.01,n=3). (2) Both E2 and acute GPR30 activation by G1 reversed stress induced increases of β2AR phosphorylation (P<0.01, n=4) and cytoplasmic expression (P<0.01, n=4), and the effect of E2 was canceled by G15 (P<0.01, n=4). (3) Both E2 and acute GPR30 activation by G1 decreased Gi activation (P<0.01, n=3) and increased cAMP level in stress state (E2+Epi: 10.82±0.63 vs. 7.40±0.34 pmol/ml Epi treated, P<0.01, n=4; G1+Epi: 10.90±0.62 vs. 7.40±0.34 pmol/ml Epi treated, P<0.01, n=4). (4) Both E2 and acute GPR30 activation increased L-type calcium current (ICa-L) in stress state in cardiac myocytes of rat (E2+Epi: -9.11±0.95 vs. -4.87±0.88 pA/pF Epi treated, P<0.05, n=5-6 ; G1+Epi: -7.57±0.44 vs. -4.87±0.88 pA/pF Epi treated, P<0.05 ,n=5) and hiPSC-CM (E2+Epi: -13.63±1.28 vs. -7.25±0.66 pA/pF Epi treated, P<0.01, n=7-8 ) which were abolished by G15 (G15+E2+Epi: -4.31±0.81 vs. -9.11±0.95 pA/pF E2+Epi treated, P< 0.01,n=6) or GPR30 knockdown (siGPR30+E2+Epi: -7.29±1.52 vs. -13.63±1.28 pA/pF E2+Epi treated, P<0.01, n=7-8) measured by whole-cell patch clamp. These data suggest that GPR30 mediated cardioprotection of estrogen against stress through rapid signaling pathway via suppression of β2AR phosphorylation, increasing the activity of Gαs-cAMP signal pathway, strengthen ICa-L and calcium transient amplitude to improve the cardiac function. Our findings provide a light for treating patient with stress induced heart disease especially for those with estrogen deficiency.