By employing the first-principles pseudopotential plane-wave method,the physical properties of zincblende ZnO are investigated in comparison with those of the common wurtzite structure.Zincblende ZnO is predicted to be a direct gap semiconductor.Compared to the wurtzite structure,the zincblende ZnO is characterized by smaller bandgap and pressure coefficient.larger electron effective mass,increasing static dielectric constants and more covalent bonding.Furthermore,the optical properties including dielectric function and energy loss function of zincblende ZnO were obtained and analysed with some features.These aspects reveal promising applications of zincblende ZnO in optoelectronic devices.