During the last decades, Digital Mock-up has been intensively developed. Various information and data are generated in each step of the Digital Chain (CAD, CAM, machining process, etc.). However, these different data haven’t been well exploited, especially, in feature modelling. Machining features, defined through their geometrical, topological, and manufacturing characteristics, must integrate the different data generated by the Digital Chain for a better characterization, specially, in the case of freeform shapes. In fact, most reported research deal only with regular shapes while freeform machining features are not well considered at present. In this paper, we propose a new characterization and definition of freeform machining feature based on digital chain extracted data. The freeform machining feature is represented as a multilevel structure and the mapping between geometrical and machining process knowledge in each layer is built.