The purpose of the present work is to investigate the effects of helium plasma treatment on tensile deformation of nano-SiO2 sol-gel coating T300 carbon fiber and provide a new concept for the nano-structural interphase between fiber surface and nano-coating. The tensile test results show that the activation volumes of T300 carbon fibers untreated and treated with helium plasma ranging from 681.9628 to 32342 nm3 by following Eyrings equation are important descriptors for the properties of the nano-structural interface between fiber surface and nano-coating, and the ductility of the nano-SiO2 sol-gel coating T300 carbon fibers treated by helium plasma is enhanced. From the results of the scanning electron microscope, X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy, it is found that the uniform dispersion of the nano-SiO2 coating of the T300 carbon fibers treated by helium plasma can not only fill the micro-flaws, but also cause the occurrence of effective activation surface interaction between carbon fibers and nano-SiO2 coating, along with the introduced activated functional groups on the fiber surfaces.