The effects of oxygen plasma treatment on tensile deformation of nano-SiO2 sol-gel coating ultra-high molecular weight polyethylene（UHMWPE） filaments are investigated and a new concept for the nano-structural interface between fiber surface and nano-coating is provided. The tensile test results show that the activation volumes of UHMWPE filaments untreated and treated with oxygen plasma ranging from 1718.448 to 16603.070 nm3 by using Eyrings equation are an important description of the properties of the nano-structural interface between fiber surface and nano-coating, in addition to the enhanced ductility of UHMWPE filaments after nano-SiO2 sol-gel coating UHMWPE filaments treated by oxygen plasma. From the results of scanning electron microscope and Fourier transform infrared spectroscopy, it is observed that the uniform dispersion of the nano-SiO2 coating on the UHMWPE filaments treated by oxygen-plasma not only fills in the micro-flaws, but also introduces the activated functional groups into the fiber surfaces.