Poly(urethane)(PU) nanofibers containing silver nanoparticles were prepared via a simple one-step method. PU was dissolved in DMAc/THF(7/3 w/w) with a small amount of $AgNO_3.Ag^+$ ions in the PU solution were reduced by DMAc into Ag nanoparticles, which was confirmed by UV-vis spectroscopy and TEM analysis. DMAc was used as a solvent for PU as well as a reducing agent for the Ag+ ions. The resulting solutions were directly electrospun into PU nanofibers. The Ag nanoparticles were all sphere shaped and evenly distributed in the PU nanofibers. The average sizes of Ag nanoparticles in PU nanofibers electro spun with 0.2 and 0.5 wt% $AgNO_3$ were 3.6 and 4.0 nm, respectively.