The All-Electric-Engine with only electrical power offtake is a main goal in aircraft system development. The use of electric-motor pumps instead of engine-driven pumps for powering the central hydraulic systems could be a part of this objective. Additionally, the concept would meet the incremental development strategy performed by the aerospace industry today and saves costs by using state-of-the-art hydraulic actuation technology. This paper describes a process for optimizing such systems regarding their architecture and design parameters. For this task a methodology for the hydraulic consumer allocation called OPAL is used and extended by an automatic power system sizing. Feasible allocations, called permutations, are determined on the basis of preliminary system safety assessments regarding multiple top failure events. In the next step an automated sizing of the permutations is performed based on simplified hydraulic load analyses. This enables a comparison of a large number of architectures in a very short time to optimize the electro-hydraulic system architecture. In the next part of the process a more detailed sizing of the electro-hydraulic system is performed for selected example architectures. Here a steady-state sizing of the power system is carried out with the Hamburg University of Technology tool ArOLab. The pipe network sizing is automated by using an optimization that finds a design that meets the performance requirements with a minimum of mass. The function is used to do a rapid evaluation of different design variables that influence the later system performance. The whole process is demonstrated by a test case study in which electro-hydraulic architectures are optimized for a mid-range aircraft.