MPLLA/NBG composite nanofibers were prepared by combination of irradiation grafting modified poly lactic acid (MPLLA) and nano-bioglass (NBG) though electrospinning technique. The effects of grafting modification of PLLA on structure and properties of the composite nanofibers were studied by FT-IR, SEM, mechanical test, contact angle and in vitro mineralization. The results show that the compatibility of PLLA and NBG can be improved by irradiation grafting of PLLA, the powder reuniting decreases as well as the fiber diameter and distribution. The transverse tensile strength of the composite nanofibers is all above 5.5 MPa and the longitudinal tensile strength increases from 3.9 MPa to 5.5 MPa. The transverse and longitudinal differences are decreased with the increasing of grafting ratio. There is no significant difference in the water contact angle of PLLA /NBG and 10%MPLLA/NBG within 20 s. While the water contact angle of 20%MPLLA /NBG decreases from 134.2° to 78.6° in 20 s, indicating the hydrophilicity increases. The in vitro mineralization property of composite nanofiber is improved through grafting modification. The 20% MPLLA/NBG is quickly mineralized in 24 h. And the degree of mineralization in 14 d is 7.88 and 6.18 times of PLLA/NBG and 10%MPLLA/NBG, respectively.