Herein, an aldehyde group mediated in situ reduction approach is presented for preparation of silver nanoparticles anchored oxidized regenerated cellulose (Ag/ORC) microfibers. During the preparation, cellulose acetate (CA) microfibers are produced by electrospining and treated with heat and alkaline to form regenerated cellulose (RC) microfibers. After oxidating the RC microfibers by NaIO4, the generated aldehyde groups on the microfibers are employed to in situ reduce Ag ions, and the formed Ag nanoparticles (AgNPs) are directly deposited on the surface of oxidized regenerated cellulose (ORC) microfibers. The structure and morphology of the composite microfibers are characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and X-ray diffraction (XRD). It is found that AgNPs with a diameter of approximately of 17.5 nm are well distributed on the ORC microfibers. Furthermore, the antibacterial activity of the prepared Ag/ORC microfibers towards Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) is assessed via disk diffusion method, live dead fluorescent imaging assay, and SEM examination. The results show that the Ag/ORC microfibers exhibit excellent antibacterial activity, providing a promising antibacterial material. (C) 2020 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.