CaGd1-xAlO4: xEu3+(CGA∶xEu3+) X-ray storage phosphors with different doping concentrations of Eu3+ were synthesized by a combustion method．In the doping concentrations range of 0~0.150, single phased CGA∶xEu3+ powders are acquired and Eu3+ occupying the sites without symmetric inversion center leads to strong red emissions. For the CGA∶0.100Eu3+ phosphor, the strongest red emission intensity can be observed. As the concentration of Eu3+ ions increases, the distance between Eu3+ ions decreases, increasing the energy transfer probability of Eu3+→Eu3+→annihilation center, and luminescence quenching occurs. When the Eu3+ doping concentration is 0.003, the strongest intensity of the photo-stimulable luminescence can be obtained. For the annealed CGA∶0.003Eu3+ phosphor in nitrogen ambient, the number of OH- groups in CGA is decreased and the red emission intensity is enhanced compared to the unannealed sample. The thermoluminescence analysis shows that there exist two kinds of traps in the CGA∶0.003Eu3+phosphors and the trap depths are 0.79 and 0.93 eV, respectively. In particular, the annealing in nitrogen leads to the increased number of traps, the enhanced photo-stimulable luminescence intensity and the improved storage properties. The nearly linear relationship between the X-ray absorbed dose and the X-ray irradiation time can be found in the range of 0~11.8 Gy. When the X-ray absorbed dose is 1.2 Gy, an imaging plate made of CGA∶0.003Eu3+ heat-treated under a nitrogen atmosphere obtains high-quality X-ray red imaging. The experimental results show that Eu3+ doped CGA X-ray phosphor materials have potential applications in computer X-ray medical imaging with CCD as photodetector