Hierarchical structure is one of preferred choices in the nature and has been widely mimicked for practical applications in the past decades. As a kind of efficient technology, layer-multiplying coextrusion has been applied to fabricate polymeric materials with alternating multilayer structure by combining an assembly of layer multiplying elements (LMEs) with two extruders. With increasing the number of LMEs, the layers tended to be multiplied and the thickness of each layer could be reduced from micron to nanometer. Herein, the crystallization behavior of semi-crystalline polymers in the multilayer structure was investigated. Studies revealed that the confined layer interfaces and layer spaces induced different crystal morphologies and types from those in bulk systems. In order to clearly clarify the crystallization mechanisms, the influence of layer structure, the type of nucleating agents and the processing conditions were considered. Besides, the distinct crystalline structure possessed the ability to resist the mechanical deformation and destruction, which provided a non-additive strategy to fabricate polymeric materials with balanced performances.