Transverse vibration of an axially moving fluid arising in the bubbfil spinning (e.g. bubble electrospinning and modifications) and the stuffer box crimping is studied. By the Hamilton’s principle, governing differential equations for an axially moving slender fiber of viscoelastic fluid is obtained. The velocity of the axial motion affects greatly the natural frequencies of transverse vibration. If transverse vibration occurs just before fiber’s solidification, a crimped fiber can be obtained, and the crimped frequency can be adjusted by the velocity of axial motion.