Power System Substation is an important part of an indispensable, it bears a power conversion and energy redistribution of the important tasks. Substation in power system voltage transformation, acceptance and distribution of electricity, control the power flow and adjust the voltage of the power facilities, it will at all levels through its transformer linked voltage power grid. In our country, 35kV substation widespread is the residents of electricity, industrial electricity guarantee. Reliable operation of the 35kV substation, directly related to the industrial and agricultural production, people's lives, and social progress. With the continuous development of the economy, especially real estate development in recent years, power supply surge load. As the country "City, rural power grid" that is, the "two net" renovation project, in order to ensure safety, quality, economic power, and better services for the regional economy, 35kV substation to ensure that the modified design for the power grid security, stability operations, to improve the quality and supply reliability of power supply has a vital role. In this paper, by searching the load of the system and the line. And information on the load, as well as the development trend line analysis, from security, economic and reliability considerations, the city of Lin'an Jin towns conducted a 35kV substation circuit design, the preparation of the design specification and the mapping of the town of Lin'an JinChen 35kV substation wiring diagram. Key words: power supply design,substation design,primary circuit design