Model-based development is a potential approach to designing complicated mechatronic systems. This paper proposes a product design framework for mechatronic systems, which integrates model-based development with prototyping and focuses on its process of deployment with hypothesis and verification. SysML is adopted as the modeling language for representing the mechatronic system without depending on specific domains, and FMEA is adopted as the method for describing the results of validation by prototyping. The DRIFT framework is used to capture designer’s operations on the design tools of SysML and FMEA and to manage its process. This study defines design concepts and design operations that are extracted from the patterns embedded in design process with SysML and FMEA. A design example of a ball-sorting robot is created using LEGO Mindstorms to demonstrate the proposed framework.