Recently, fiber optics have become indispensable infrastructural components for the transmission of optical signals and energy. We provide an overview of functional fibers. The light guiding mechanism and preparation scheme of microstructure optical fibers (MOFs) are introduced. The usage of MOF has emerged in optoelectronic sensing and laser applications because of its flexible preform preparation, hollow core transmission ability, and ultralow theoretical attenuation. Because the development of optical fibers is progressing toward the integration of multi-functional units into single fibers, the preparation and potential applications of a nanomechanical optical fiber are introduced in detail. This new type of optical fiber represents a crucial research direction for the development of all-optical devices and optical integration technologies.