The structure and morphology of electrospun nanofibers largely determine their properties and performance. In order to develop functional nanofibers, it is very necessary to tailor the structure and control the morphology. This chapter introduces different morphologies of polymeric electrospun nanofibers, and describes the effects of operation parameters on nanofibers’ morphologies. It also introduces different structures of obtained electrospun nanomaterials and their unique applications. Great efforts have been devoted to studying the fabrication process as well as the characterization of electrospun nanofibers. Numerous work has been done to illustrate the morphologies and properties of electrospun nanofibers as a function of process and material parameters by many researchers in different groups. The transformation of the polymer from solutions to electrospun nanofibers can be affected by solution parameters, processing parameters, and ambient parameters. The controllable surface morphologies of the electrospun products can be realized, such as random or aligned fibers, smooth or rough surfaces, hollow and porous morphologies, and bends or beaded structures.