Technological change from mechanics to intelligent technical systems leads to a fast evolution of products, which is characterized by manifold product versions and generations. To cope with this change, companies need to systematically manage product evolution in terms of concerted innovation and adaptation steps. In this context, developing a technical system in release projects seems to be a promising approach. However, this requires a systematic planning process equally taking into account market strategic and technical aspects.Against this background a systematic approach for release planning of intelligent technical systems is developed in this thesis. It structures the planning process in strategic, tactical and operational release planning. Strategic release planning schedules the initial release plan and determines release types and dates. Tactical release planning assigns new product features and technical changes to these releases. Operational release planning finally determines the actual release content taking into account the available resources. Necessary process models and tools support the implementation of this hierarchical release planning process. The approach is finally applied to an electric control valve.