In order to study the sensitization of Ce ions co-doped in ZnWO4 laser crystals doped with Nd or Eu ions, macro-defect-free Nd:ZnWO4, Ce:ZnWO4, Eu:ZnWO4, Ce:Nd:ZnWO4 and Ce:Eu:ZnWO4 crystals were grown by the Czochralski method. The X-ray diffraction (XRD), absorption spectrum and fluorescence spectrum of the crystals were measured. The results of measurement indicated that the strong absorption of Ce3+ ions in ZnWO4 crystals at 324 nm can absorb pump energy effectively and the energy transfer exists between Ce3+ ions and Nd3+ ions as well as Eu3+ ions obviously. It enhances the intensities of the up-conversion fluorescence (at 474 nm and 572 nm) of Nd3+ ions and the fluorescence (at 613 nm) of Eu3+ ions. The sensitization mechanism and the energy transfer processes are presented. The results demonstrated that the sensitization of Ce ions co-doped in ZnWO4 laser crystals doped with Nd or Eu ions has better performance on enhancing the luminescence intensity of laser crystals.