Abstract: Ultrafine nano-hydroxyapatite(nHA) /silk fibroin(SF)/poly( ε-caprolactone)(PCL) composite fibers were prepared via electrospinning. Scanning electron microscopy(SEM), attenuated total reflectance-Fourier transform infrared spect roscopy ( ATR-FTIR) and X-ray diffraction(XRD) were used to characterize the electrospun ultrafine nHA/SF/PCL composite fibers. The mechanical properties of fibers were also tested. The results show that the diameter of the fibers decreases and the crystallinity of PCL in the fibers becomes poor with increasing nHA content in the fibers. Compared with SF/PCL fibers, the mechanical properties of ultrafine nHA/SF/PCL composite fibers are still well when the nHA mass ratio is 30 % in the fibers. In vitro mouse fibroblast (L929) cell culture indicates that the ultrafine nHA/ SF/PCL composite fibers are non-toxicity.