▎ 摘　　要

Introducing graphene into polymers is a common method to prepare nacre-like functional composites with enhanced mechanical strength and conductive properties. However, the soft nature of graphene sheets makes it easy to form chaotic wrinkles and degrade the mechanical performance of the composites by hindering interlayer stress transfer. Here, we use a simple plasticization and stretching method to flatten the sheet wrinkles and obtain a highly oriented and crystalline graphene-based nacre-like composite film. The composite film shows excellent mechanical properties (tensile strength of 709.2 MPa, toughness of 11.1 MJ m-3), as well as high electrical conductivity of 7671 S m-1, which are much higher than those of as-prepared films without plasticization and stretching. This low cost and facile method opens an avenue to prepare graphene and other 2D nanosheet based composites with enhanced performance.