At present, there exists a widely-held view that electric field plays an extremely important role in the electrosprayprocess. Aimed at investigating into the effects of electric field distribution and intensity on the electrospray process andresultant microsphere diameter, a variety of necessary and relevant tests were performed in this study by inviting an auxiliaryelectrode ring. The three-dimensional electric fields of the electrospray system were simulated, in addition, high-speedphotography was adopted to recognize the electrospray modes. The results of a series of electrospray experiments demonstratedthat not only electrospray mode but also resultant microsphere diameters are influenced, to a considerable degree, by the electricfield. Such simulation results were verified by above-mentioned experiments that from higher electric field intensity comessmaller microsphere diameter, due to the fission caused by the surface charge, and besides, more uniform electric fielddistribution produces more uniform microsphere diameter.