As a typical representative of the third generation energetic materials， 2，4，6，8，10，12-hexanitro-2，4，6，8，10，12-hexaazaisowurtzitane （CL-20） is currently the most powerful energetic compound that has already been commercially available. The important research directions are， at present， the optimum synthesis of CL-20 and the preparation of CL-20-based high energy and low sensitivity energetic compounds in the development of energetic materials. The development status of the intermediates in the preparation of CL-20 was analyzed and summarized. The solutions and prospects of the intermediates were also proposed. In addition， the research progress， structural characteristics and main properties of CL-20 crystal products were also discussed. Through sorting out the synthesis and crystals of CL-20， it is concluded that low-cost， high yield， high purity and environmental friendliness are the future development direction of the synthesis process of CL-20.