Ca(NO3)2·4H2O, Eu(NO3)3and H2C2O4·2H2O were adopted tosynthesize CaO:Eu3+ with the chemical co-precipitation method, and the effects of the calcination temperature and Eu3+doping concentration on the phosphor structure and its luminescent properties were investigated by TG-SDTA, XRD, and PL-PLE. The results confirm that the Eu3+ ions as luminescent centers substi-tutes Ca2+ sites without changing the crystal structure of cubic CaO. The optimum calcination tem-perature and the optimum concentration of Eu3+ are 1 100 ℃ and 1 mol%, respectively, under which the best crystallinity and highest PL intensity appeared. The maximum emission wavelength is 592 nm (5D0→7F1) which is excited by xenon lamp with the wavelength of 200-280 nm, indicating that the Eu3+ ion mainly locates in the symmetric position (Oh) in the crystal lattice of CaO.