To synthesize high-performance rare earth composite luminescent materials, blue fluorescent Nitrogen Doped Graphene Quantum Dots (N-GQDs) were prepared by hydrothermal method, and an N-GQDs modified composite luminescent material UiO-66-(COOH)₂-Eu was prepared by post-synthetic modification method. The structural morphology of the composite luminescent material was characterized using Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy. The fluorescent and luminescent properties of the composite material were tested, and the effect of N-GQDs dosage on the luminescent properties was discussed. The results show that the obtained composite luminescent material has good stability and fluorescent properties, and a small amount of N-GQDs can improve the luminescence intensity and prolong the fluorescence lifetime of the composite material.