Wireless power transfer (WPT) systems in railway systems, as a multidisciplinary complex problem, are required to efficiently improve an objective function (e.g. transfer efficiency, mass of a system) while satisfying various constraint functions such as electromagnetic field (EMF), air-gap, and power capacity transferred. In this paper, the optimization framework for the railway-specific wireless power transfer systems was developed and applied to minimize the mass of a wireless power transfer system. After optimization, the mass of the system could be reduced by 26.26% while transmission capacity and EMF were satisfied. The proposed framework would help us to reduce time and cost for development.