Overcoming blood-brain barrier (BBB) for precise glioma diagnosis remains an urgent challenge due to its peculiar location in central nervous system (CNS). Herein, polymer-coated carbon nanodots with high hydrophilicity were facilely married with Gd-DTPA to construct a dual-modal imaging system (NCDDG). This system was demonstrated with obviously decreased toxicity and enhanced magnetic resonance imaging (MRI) ability compared to traditional Gd-DTPA. Meanwhile, NCDDG reserved the bright fluorescence of biocompatible carbon nanodots with increased spatial resolution. Attributed to small size and hydrophilic polymer coating, NCDDG was capable of overcoming the BBB and permeating leaky microvascular walls into surrounding glioma tissues via prolonged in vivo circulation and enhanced retention effect. As a result, dual1-modal targeted MR/fluorescence imaging of glioma was synergistically achieved with high sensitivity and resolution. This work promised a potential contrast agent for sensitive clinical diagnosis of glioma.