Objective To determine whether dopamine D5 receptor (D5R) regulates the development of dilated cardiomyopathy (DCM) by inhibiting oxidative stress. Methods We developed heart-specific hD5 mutant (α-MHC-hD5F173L) and wild type (α-MHC-hD5WT) transgenic mice. The NOX2 expression and ROS production were tested in the transgenic mice at three month of age. The α-MHC-hD5F173L mice were treated with either NADPH oxidase inhibitor Apocynin (1mmol/kg/day) or phosphate-buffered saline (PBS) as control by intraperitoneal injection for 4 weeks. After then, the indexes of heart function were measured. The hD5WT and hD5F173L were transfected respectively in rat H9C2 cells, in which ROS production and NOX2 expression were detected at basal level. Results The ROS production and NOX2 expression were higher in the heart of α-MHC-hD5F173L than α-MHC-hD5WT mice. Apocynin treatment improved the heart function of α-MHC-hD5F173L mice. NOX2 expression and ROS production were higher in hD5F173L than hD5WT transfected H9C2 cells. Conclusions Dopomine D5 receptor may prevent DCM development by inhibiting oxidative stress.