ZnO nanofibers were fabricated by electrospinning method. The morphology and microstructure of the as-prepared ZnO nanofibers were studied in details. The ZnO nanofibers showed pure polycrystalline phase with the hexagonal wurtzite structure. The average diameter of the ZnO nanofibers, calcined at 550 A degrees C, was around 140 nm. Moreover, the electromagnetic loss properties of the as-prepared ZnO nanofibers were investigated. The mechanism of dielectric loss could be attributed to the electric dipolar polarization and interface polarization. The mechanism of magnetic loss properties were mainly caused by natural resonance and exchange resonance. The networks of ZnO nanofibers also facilitated dissipating electromagnetic energy. The dielectric loss factor tan delta(epsilon) was around 0.06085 and the magnetic loss factor tan delta(mu) was approximate 0.04095. The as-prepared ZnO nanofiber exhibited excellent electromagnetic loss properties and it could be usd as a potential candidate for lightweight microwave absorption material.