Silkworm cocoons illustrate excellent puncture-resistance performance after an insight into their layers while a clear understanding of the correlation between the excellent puncture property and the silk secondary structure is still lacking. Herein, we peeled silkworm cocoon into eight layers, and a combination of examination techniques including scanning electron microscopy, tensile mechanical test, Fourier transform infrared spectroscopy, Raman spectroscopy, and X-ray diffraction were applied to figure out the morphologies (surface and cross-section view), mechanical properties, secondary structure, the content of β-sheet, and crystallinity of each layer's fibroin after degumming. The results indicated that the fifth layer offers a higher level of puncture-resistance than the other layers except for the eighth layer. Additionally, a high content level of β-sheet structure and high crystallinity gives rise to the high puncture strength as for hierarchical silk fibers. In general, the new finding holds great potential inspiration for the design of puncture-resistant composites.

蚕茧在深入了解其层数后显示出优异的抗穿刺性能，而对优异的穿刺性能与蚕丝二级结构之间的相关性仍缺乏清晰的认识。在此，我们将蚕茧剥成八层，结合扫描电镜、拉伸力学试验、傅里叶变换红外光谱、拉曼光谱和X射线衍射等检测技术，对蚕茧的形貌（表面和交叉截面图）、力学性能、二级结构、β含量-片材，以及脱胶后每层丝心蛋白的结晶度。结果表明，除了第八层之外，第五层提供了比其他层更高水平的抗穿刺性。此外，β-折叠结构的高含量水平和高结晶度使分层丝纤维具有高穿刺强度。总的来说，这一新发现对抗穿刺复合材料的设计具有很大的潜在启发。