Historically, European Lower Paleolithic cultures have been divided according the presence or the absence of bifacial tools. In order to go beyond this typotechnological classification of Homo heidelbergensis groups, we now question socio-economic behaviors. These are identified by territorial, functional and technical analysis. That involves the study of the whole lithic production chaîne opératoire from raw material gathering to the making and use of stone tools and how they are abandoning or carry away from the site. Also, we confront the results from lithic studies to other data from pluridisciplinary studies (archaeozoology, paleoenvironment…). Here we present a techno-morphological and functional approach of bifacial tools, flakes, flake-tools, and small flakes resulting from resharpening. Functional studies on Lower Palaeolithic tools are rare because of the difficulties to work on such an old material. We chose to apply this combined approach on the main archeological level (P) of Soucy 3 (Yonne, France) dated to MIS 9, thanks to the well-preservation of tools and their great diversity. This archeological layer is contained in a fluvial sequence and has yielded the higher quantity of bifacial tools observed in Europe. Both the technological and the functional analysis gave us similar results on techno-economics behaviors and activities that took place on the site. This promising work need to be continued to give us more information about sites function and anticipation capacity of Lower Palaeolithic human groups. New elements on the use and the lifetime of bifaces and other tools emerge from this work