It is very desirable to design dual-mode nanocomposites for diagnostic applications via flexible strategies. Herein, we proposed to synthesize one type of multifunctional magnetic resonance (MR)/optic nanocomposites based on manganese ferrite magnetic nanoparticles (MFNPs) modified by fluorescent podoplanin (PDPN) antibodies. MFNPs were synthesized using a thermal decomposition method and were modified by the fluorescent PDPN antibodies on their surfaces. The fluorescent PDPN antibody-conjugated MFNPs enabled strong MR imaging and fluorescence imaging due to the antibodies that targeted brain tumors. These results demonstrate that MR/optic nanocomposites have potential as precision diagnostic systems for brain cancer.