Multilayer assembly is regarded as one of preferred structures in the nature and has been widely mimicked in the past decades. It is widely recognized that the parallel-distributed interfaces can not only separate different compositions or phases, but also act as mass or energy transition which plays a significant role in tailoring microstructures and final performances. Herein, three aspects correlating to the contribution of multilayer interfaces are concerned: (1) Gradient distribution of molecular relaxation. Compatible poly(vinylidene fluoride) and poly(methyl methacrylate) were alternately organized forming multilayer architecture. The interfacial diffusion not only broadened the relaxation distribution of amorphous chains, but also strengthened the interaction between amorphous and crystalline domains. As a result, an outstanding multi-shape memory effect with high shape-fixing and -recovery capacities was achieved based on high phase continuity and broad thermal-transition temperature. (2) Competitive growth of crystalline structure. Transcrystallinity (TC)/α-spherulite multilayered crystalline structure was generated in polypropylene through selective distribution of α-nucleating agents. Specially in TC structure, an α-β crystal transition was encouraged during the confined growth around layer interfaces. Therefore, both the mechanical strength and flexibility were improved by virtue of the formation of highly-oriented TC and controllable content of β crystals. (3) Synergistic effect of multi-functional networks. Flame retardants and carbon nanotubes were alternately distributed in thermoplastic polyurethane. The impedance difference between conducting and flame-retarding layers dramatically enlarged the shielding effectiveness, whereas intumescent effect of flame-retarding layers promoted the production of continuous carbonaceous structure together with adjacent conducting layers in combustion, which overcomed the major disadvantage of the composite made by conventional methods. Keywords: multilayer structure, interface, property, synergistic effect