Novel uniform straw-like Fe3O4/Se one-dimensional (1D) nanoplank bundles have been successfully prepared by a facile and green glucose-reducing method at gentle temperature for the first time. The width, thickness, and length of as-prepared Fe3O4/Se nanoplanks can be observed at the range of 300−400 nm, 50 nm, and 6−8 μm, respectively. Fe3O4 nanoparticles may act as seeds and catalytic agents for the formation of the bifunctional nanocomposites. The products bear both fluorescent and superparamagnetic properties. More importantly, quantum size effect in optical properties, which is reflected by a marked blue shift of the band gap and direct transitions relative to the values of bulk t-Se, can be observed. The mechanism of formation can be described as the linear aggregation and growth of Fe3O4/Se nanospheres and the self-assembly of 1D Fe3O4/Se nanoplanks. The strawlike Fe3O4/Se can be potentially converted to a series of bifunctional nanocomposites (e.g., Fe3O4/Ag2Se, Fe3O4/Bi2Se3, and Fe3O4/CdSe) with special morphology via the sacrificing template method. This method might provide a new, mild, and economical concept for the synthesis and construction of nanowires, nanobelts, nanorods, and some other kinds of 1D nanostructures. Moreover, this novel bifunctional nanocomposites will open up a potential and broad application in microelectronics, biology, and medicine.