An understanding of the composition, structure and property relationship is essential for engineering high performance polymer nanofibers to meet the ever-increasing demands for various applications. Here, bi-phasic polymeric fibres were prepared using electrospinning followed by thermal bonding. By controlling the softness-stiffness of the composition and configuration, the mechanical properties of biphasic fibrous films were improved with the strength up to eight times higher than that of single counterparts. We demonstrate that compatible interfaces, increasing alignment, supramolecular chains and connected bonding points, are jointly responsible for the mechanical enhancement except the diameter previous thought. This strategy provides new ideas and directions to design high-performance materials, especially for polymer-based fibrous material. (C) 2017 Elsevier B.V. All rights reserved.