In the current research, europium doped ZnO nanopowders prepared by a microwave hydrothermal method are investigated. The effects of synthesis pressure on the morphologies, crystal structures, and optical properties of Eu-doped ZnO were analyzed by scanning electron microscopy, X-ray diffraction, cathodo-and photoluminescence. From our investigations it can be concluded that the synthesis pressure strongly influences the surface morphology. With the increase of the synthesis pressure from 2 MPa to 10 MPa significant changes can be observed. An increase of the mean crystallites sizes and change of the intensity ratio between the near band edge and defect related deep level emission band of ZnO were observed.