In this study, by manipulation of hemisphere location of Bhargava electrospining system and some small changes in set-up of the pervious technique, polyethylene terephthalate (PET) hollow nanofiber yar was produced. Electrospinning was done between two syringe needles, then electrospun nanofibers collected on hemisphere surface and twisted by rotating the hemispherical collector. In order to produce core-sheath yarn, a PVA multifilament yarn was fed as the core from feeder unit to take up unit by hollow metal rod that attached to the hemispherical collector. PET nanofibers were twisted onto the PVA yarn as the sheath, and then core-sheath yarn was drawn and collected on take up roller. Hollow yarn was obtained by removing the PVA yarn by dissolving in water at 60 °C for 24 hours. In order to produce an optimum hollow nanofiber yarn, the covering was done six times on the core with concentrations of 18%, 21%, 24%, 27% and 30% w/v PET polymeric solution in TFA/DCM 70:30 solvent mixtures. In series of experiments, the applied voltage, the flow rate and the yarn twist were kept constant at 10 kV, 0.0526 ml/h and 1851 TPM, respectively. In surveying the electrospining parameters observed that the thickness of sheath increased with increasing concentrations of PET polymeric solution. Results showed that in the concentration of 18% w/v PET polymeric solution in TFA/DCM 70:30 solvent mixtures, the efficiency of extracting the PVA multifilament from the hollow yarn is more than 85%. In surveying the strength and moduls value for PVA multifilament yarn, core-sheath yarns and hollow yarns, results showed that the PVA multifilament yarn and the product hollow nanofiber yarn in concentrations of 30% w/v PET polymeric solution had the highest and lowest average strength respectively. Also observes showed that PVA multifilament yarn, core-sheath yarns and hollow yarns didnt have any significant different on average extension. In order to determine the wicking property of hollow yarns in different concentrations of polymeric solution, the wicking coefficient for each hollow yarn was surveyed. Results showed that the product hollow nanofiber yarn in concentration of 24% w/v PET polymeric solution had the highest coefficient wicking. More the regain moisture of hollow yarns were surveyed and concluded that the product hollow nanofiber yarn in concentrations of 18% w/v PET polymeric solution had the highest regain moisture. Key Words: Electrospinning, Nanofiber, Hollow yarn, Core-sheath yarn, Concentration, Wicking, PET polymeric solution, PVA multifilament and Regain moisture.