Based on a modified coaxial electrospinning process and suitable selection of solvent mixtures as sheath fluid, a new strategy is presented for systematically improving polymer nanofiber quality. A concentric spinneret with an indented inner capillary is designed for the modified coaxial electrospinning. With a solution of 12% w/v PVP K60 in ethanol as the core electrospinning fluid, six solvents are used as sheath fluids to investigate the impact of solvent properties on the resultant PVP nanofiber quality. The PVP nanofiber quality is closely related to solvent physical‐chemical properties. High quality PVP nanofibers of average diameter 130 ±10 nm with homogeneous structures and smooth surfaces are created using a solvent mixture of acetone, ethanol and DMAc in the ratio of 3:1:1(v/v/v). A new strategy is put forward for improving electrospun polymer nanofiber quality. A concentric spinneret with indented inner capillary and suitable selection of the solvent mixture as sheath fluid are key factors to fulfill a modified coaxial electrospinning process, by which PVP nanofibers with a diameter of 130±10nm, homogeneous structure and smooth surface are successfully created.