In this study, a novel electrospinning process using a rotating water collector is investigated for simple fabrication of circumferentially aligned polymer nanofiber mats. To use a liquid collector in electrospinning can offer several advantages over a conventional solid collector. For example, one can produce complex nanofiber structures such as stand-alone membranes and three-dimensional scaffold more efficiently. Because the previous studies have mainly focused on the use of stationary liquid collectors, the present study investigates the electrospinning process on rotating water flow. A simple electrospinning setup where a rotational speed of water flow is controlled by a magnetic stirrer is prepared. The electrical conductivity of the water collector is also modulated by dissolving sodium chloride. In this manner, the electrospun polymer nanofibers can be directly collected on the rotating water surface. The fabricated nanofibers tend to align in the same direction as the rotating water surface, thereby forming a circumferentially aligned structure. In addition, a degree of alignment is found to be improved with increasing the rotational speed. It demonstrates a strong relationship between the morphology of nanofibers and the velocity of the moving water collector. The increased electrical conductivity of water collector makes a smaller nanofiber mat while there is no significant effect on the nanofiber alignment. It may be attributed to the reduced repulsion between electrospun nanofibers because of the enhanced removal of electrical charges in them. The present study can be used as a useful tool to manipulate the electrospun nanofibers and control the complicated structure of nanofiber mats.