Abstract:Application of 20kV in MV distribution system has been proved to be feasible and advisable with the rapid growing load density in urban areas. Preliminary conclusion about reasonable load density of higher than a certain level is appropriate for voltage sequence in power supply system in special conditions is presented. According to the new situation of the development of economic society and power network .made a strategic decision to adopt 20kV distribution power network for solving the outstanding and contradictory problem in distribution network development and changing the development mode of distribution. The paper presented electrical primary design idea for 220/20kV substation. The project combined with new technology of new era requirement, the standardization and the energy-saving designing principles of 220/20kV substation design has commenced. Analysis is taken from the main wiring, electrical equipment selection and plane arrangement of 220/20kV substation for reference.