As for today, the assurance of the reliability and safety of mechatronic systems is still a problem not solved sufficiently. Indicators for this are the product recalls of the last years. The most of the failures result from insufficient communication and cooperation of the involved disciplines. In addition, the established assurance methods of today typically require a detailed system design as their input and are therefore applied at a comparatively late stage. Furthermore, the increasing interdisciplinarity leads to a higher system complexity that needs to be dealt with. A solution approach for overcoming the outlined challenges is the early assurance of reliability and safety based on the discipline-spanning specification of the product conception. In this thesis, a systematics for the early assurance of reliability and safety of advanced mechatronic systems has been developed. It contains five main constituent parts: a structured procedure model, a method for the selection and planning of the assurance methods, a specification language for the description of the product conception with the consideration of reliability and safety related information, methods for analysis and improvement of the product conception as well as a concept for a software tool support.The validation of the systematics takes place based on the X-by-Wire experimental vehicle Chamaeleon that has been developed on the Chair for Control Engineering and Mechatronics of the Heinz Nixdorf Institute. It is shown that the systematics supports the identification and removal of the weak points of the product conception with regards to safety and reliability.