The major topic covered in this paper is fabrication and performance study of polyacrylonitrile (PAN) ultrafine fibers from high-concentration solutions via a vibration-electrospinning technique. The influences of ultrasonic vibration on the solution properties of high viscous PAN solution as well as surface morphology and mechanical performance of PAN fibrous mats were investigated. The results indicated that: (1) the effect of ultrasonic vibration on the mechanical properties was significant; (2) the vibrorheological effects of ultrasonic vibration appeared not only in dramatic reduction of polymer viscosity, but also in improvement of the electrospinnability of polymer solutions; (3) fibers with smaller diameter, better uniformity and fewer surface defects were prepared with the application of vibration; and (4) the tensile strength of membranes was substantially enhanced at optimized vibration parameters comparing that without vibration treatment.