There are various nanostructures in biological system. They are made of biological molecules via self-assembly with well-organized architectures and specific functions. These nanostructures can be grouped into lines, layers and cages, corresponding to one-, two- and three-dimensional structures, respectively. The bionanostructures can serve as the models or templates for biosynthesis of biodevices with desired functions by rational design. Proof-of-concept studies have shown their attractive performance in practical applications, e.g., biosensors, catalysis, tumor thermo-therapy, drug delivery, tissue engineering, and batteries.