Magnetic nanoparticles have been one of the most attractive nanomaterials for various biomedical applications including magnetic resonance imaging (MRI), diagnostic contrast enhancement, magnetic cell separation, and targeted drug delivery. Three-dimensional (3-D) fibrous scaffolds have broad application prospects in the biomedical field, such as drug delivery and tissue engineering. In this work, a novel three-dimensional composite membrane composed of the tri-block copolymer poly(ε-caprolactone)-poly(ethylene glycol)-poly(ε-caprolactone) (PCL-PEG-PCL, PCEC) and magnetic iron oxide nanoparticles (Fe3O4 NPs) were fabricated using electrospinning technology. The physico-chemical properties of the PCEC/Fe3O4 membranes were investigated by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD) and differential scanning calorimetry (DSC). Morphological observation using scanning electron microscopy (SEM) showed that the composite fibers containing 5% Fe3O4 nanoparticles had a diameter of 250nm. In vitro cell culture of NIH 3T3 cells on the PCEC/Fe3O4 membranes showed that the PCEC/Fe3O4 fibers might be a suitable scaffold for cell adhesion. Moreover, MTT analysis also demonstrated that the membranes possessed lower cytotoxicity. Therefore, this study revealed that the magnetic PCEC/Fe3O4 fibers might have great potential for using in skin tissue engineering.