Crystalline-ionic conductors of lithium ions have been investigated since 1970s. They showed lower conductivity than silver and copper ones. Recently, new super lithium ionic conductor, LGPS system was designed and developed. This material showed quite high conductivity, 12 mS/cm, but, its structure was completely new and unknown. By the assistance of crystallographic software using an ab initio method, the unknown structure was solved from multi-probe powder diffraction data. That type of software is really necessary on the material searching field.