Glutamate is a biomarker for many nervous system diseases, and sensitively detecting glutamate is meaningful in the clinic. Therefore, a unique 3D framework of Cd-MOF (1) is synthesized and characterized. A single-crystal X-ray study reveals that it is a two-fold interpenetration (4,4)-connected framework with a PtS topology, where a large 1D rhombic channel with a size of 8 X 14 angstrom exists and the total potential void volume can reach 62%. Luminescence results demonstrate that 1 has good luminescence stability and can sensitively detect glutamate in water with a detection limit of 1.15 X 10(-7) mol/L, which makes it the most sensitive MOF-based luminescence sensor of glutamate to date. More importantly, it also can serve as a luminescence sensor to detect glutamate in serum, and the quenching concentration needs to be only 43.1 mu mol/L, which is much lower than the harmful level of glutamate (400 mu mol/L) in glioma patients' blood. Compound 1 can be used at least five cycles. These results show that 1 has a potential application in monitoring glutamate in clinical scenarios.