Abstract: The developments of synthesis routes and production technologies of CL-20 in the last two decades are reviewed. The research achievements in condensation，debenzylation，nitrolysis and crystal transition are summarized，discussed and analyzed. Most of these achievements were obtained during the end of last century and the beginning of this century. In addition，the novel three-step synthesis route of CL-20，which appeared in the literature in 2004，is also introduced in some detail. CL-20 is obtained directly in this route，by nitration of the hexasubstituted hexaazaisowurtzitane derivatives formed by reaction of the α，β-dicarbonyl derivatives with other primary amines rather than benzylamine. This new technology might be significant in lowering the production cost of CL-20.