C1q-tumor necrosis factor-related protein-3 (CTRP3) is an adipokine， which exerts protective function in ischemic or diabetic heart injury. However， the role of CTRP3 in cardiac hypertrophy remains unclear. The aim of this study was to investigate the pharmacological effects of CTRP3 on pathological cardiac hypertrophy induced by hypertension. Male C57BL/6?J wild-type (WT) mice， Ctrp3 knockout mice， and mice infected with lentivirus overexpressing mouse Ctrp3 underwent sham surgery or transverse aortic constriction (TAC) surgery. After 4 weeks， cardiac hypertrophy， fibrosis， and cardiac function were examined. Compared with WT mice， Ctrp3 deficiency substantially impaired contractile dysfunction， exacerbated the enlargement of cardiomyocytes and myocardial fibrosis， and reprogramed the expression of pathological genes after TAC. Conversely， CTRP3 overexpression played a role in restoring the left ventricular cardiac contractile function， alleviating cardiac hypertrophy and fibrosis， and inhibiting the expression of hypertrophic and fibrotic signaling in mice after TAC. Furthermore， CTRP3 regulated the expression of the p38/CREB pathway and of the primary modulating factors of the endoplasmic reticulum stress， i.e.， GRP78 and the downstream molecules eukaryotic translation inhibition factor 2 submit α， C/EBP homologous protein， and inositol-requiring enzyme-1. Further， inhibition of p38 MAPK by SB203580 blunted the ER stress intensified by Ctrp3 deficiency. In vitro， CTRP3 protected neonatal rat cardiac myocytes against phenylephrine-induced cardiomyocyte hypertrophy. We conclude that CTRP3 protects the host against pathological cardiac remodeling and left ventricular dysfunction induced by pressure overload largely by inhibiting the p38/CREB pathway and alleviating p38-induced ER stress.