As the power demand has increased and power industry deregulation has progressed, the transmission and distribution system will have more complicated problems by the influence of investment reduction and NIMBY phenomena for overall power system. It is expected that the route length per MW demand will reduce gradually from 0.6[C-km/MW] to 0.53 [C-km/MW] in 2010. This comes up to a real serious problem of system planning and operational viewpoints. HTS technologies related to power system have properties to solve these complex transmission and distribution constraints, especially for metropolitan area, in the future. As the HTS technology has developed, the HTS cable technology can be the most effective alternative to solve the future expected power network constraints. This paper describes the application methodology of developing 22.9㎸ HTS cable by CAST for practical distribution system. 22.9㎸ HTS cable under development with step-by-step application methodology can substitute the existing and planning conventional 154㎸ cable. If this scheme is applied, part of downtown 154㎸ substation of metropolitan city such as Seoul can be changed into 22.9㎸ switching station. It can give great economic, environmental and additional benefits to all of the concerned authorities.