An improved free surface electrospinning for high throughput of nanofibers by utilizing micro-bubble solution system has been successfully developed in the present paper. Compared with the conventional solution system based free surface electrospinning, more jets were observed to form on the edges of the stepped pyramid shaped spinneret simultaneously and nanofibers similar in quality (diameter, diameter distribution) were produced. In addition, the effect of bubble size on the diameters of nanofibers is experimentally studied, revealing that the smaller bubble size favors the smaller diameter. This novel solution system based free surface electrospinning will benefit to the development of free surface electrospinning. (C) 2015 Elsevier B.V. All rights reserved.