中文摘要：

宇宙线发现100年来极大地推动了粒子物理学、天体物理学的发展，然而其起源、加速和传播的问题依然是宇宙线研究的三个根本问题。宇宙线“膝区”物理的研究是解决宇宙线这些基本问题的途径之一。简要回顾了宇宙线研究的历史和能谱特点；重点阐述了宇宙线“膝区”的实验观测数据以及重要实验组测量的差异和争论的焦点；归纳讨论了解释宇宙线“膝区”成因的四种主要理论模型，并结合最新实验数据说明了第四种成因（新物理过程）的可能性不大；叙述了国内研究者对宇宙线“膝区”物理研究的贡献；最后对宇宙线“膝区”物理研究的前景进行了展望。

英文摘要：

Cosmic rays have been discovered for one hundred and one years, it plays a significant role in particle physics and astrophysics. However, the origin, acceleration, propagation of cosmic rays is still a mystery, the knee region physics of it is a critical problem. Firstly, we introduce the histories and spectrum structure of cosmic rays briefly. Secondly, the observations, the discrepancies and hot spot of argument among several important ground-based arrays experiments are summarized, especially such as the Tibet ASy Array and the KASCADE Array. We also introduce the outstanding theory work of Dr. Hr6andel. Thirdly, numerous mechanisms are proposed to explain the knee structure in the all-particle spectrum. In the article basic ideas of several models are summarized, including diffusive accelera- tion of cosmic rays in shock fronts, leakage from the Galaxy, interactions with background particles in the interstellar medium, as well as new high-energy interactions in the atmosphere. Combined with the new results of LHC, we conclude the new high-energy interactions between the cosmic rays and the atmosphere almost doesn＇t exist. Fourthly, the remarkable and convincing result on the structure in the all-particle spectrum of the Tibet AST array, the new result from 5 ~200 TeV of the ARGO-YBJ array are summed up, the two arrays are located in the Tibet Antonymous Region of China. The prominent work of some Chinese scientists is also introduced, and new models can explain the common origin of the subtle features of the cosmic ray spectra, such as the knee of cosmic ray spectra and the excesses of electron/positron fluxes recently observed by ATIC, H.E.S.S., Fermi-LAT and PAMELA. Lastly, we prospect the future outlook of knee region physics. We point out the Yangbajing International Cosmic rays observatory is the optimum place to observe the knee fine structure because of the best conditions, such as the suitable altitude （4300m.a.1）, more than twenty years observations, convenient transportation, ample power