High-quality ZnO and Cd-doped ZnO nanorods with different Cd-doping concentrations are synthesized by using the hydrothermal method. Microstructures and photoluminescence of the samples are systematically investigated by SEM, X-ray diffraction (XRD), Raman scattering spectrum and photoluminescence (PL) spectrum. Results of XRD analysis indicate that ZnO and ZnO:Cd crystallites exhibit a hexagonal wurtzite structure. SEM shows that the nanorods become smaller due to Cd doping. There is an internal tension which induces the decrease of optical band gap in Cd-doped nanorods. Cd-doping increases the intensity of violet emission peak near 2.90 eV and the blue emission peak located at 2.67 eV appears when the doping concentration is up to 2%. This study can be used for developing blue-violet-emitting devices.