Abstract: Appropriate selection of the short circuit voltage of the main transformer is one of the key problems in the planning and design of the substation, which determines the security, reliability, and economy during the substation operation. Firstly, functional relationships are established theoretically based on the impedance model of transformer available for the short circuit analysis. The functional relationships contain parameters of short circuit voltage and short circuit current, parameters of short circuit voltage and reactive power compensation. On these bases, the optimization design method is presented considering two constraints, including short circuit current level and reactive compensation capacity. Case study on the design of typical 220 kV substation verifies the correctness and effectiveness of the proposed method for the optimization of the parameters of short circuit voltage.