Parameter survey is performed to obtain shape and fundamental specifications for the 15 kWh/100 MW power system stabilizing superconducting magnetic energy storage. Using the scaling law for ideal toroidal coils and J c -B characteristics of several high temperature superconductors, three fundamental specifications to minimize amount of the superconductor are obtained. In the results the optimum parameters of Bi are 4.2 K-16 T for Bi2212 (tape) and 20 K-10 T for Bi2212 (tape). And the optimum parameter of Y123 is 2 T under the condition of 77 K. But Y123 is expected to have another optimum parameter in lower temperature. Assuming an actual conductor shape, structural analysis is performed in the typical case of 4.2 K-16 T. In result, the reinforcement member area is obtained.