Aircraft sheet metal part is an important part of the aircraft structure, which has the characteristics of large quantity and shape variety. The time consumed in the production process of aircraft sheet metal parts occupies a large proportion in the process of aircraft development. Current production process through the functions provided by the existing CAD software cannot meet the requirements of modern aircraft design and manufacture in terms of efficiency and quality. Research and development of relevant automatic design and manufacturing system for aircraft sheet metal parts have become an urgent demand. Recognition and extraction of basic features of parts based on B-rep model are the basis and premise for subsequent related process planning and manufacturing. Aimed at this, this paper proposes the basic feature model of parts and presents a feature recognition algorithm based on same-side face. That is, with the STEP data as input, the web faces on both sides of parts are selected. Using the methods of attribute adjacency graph (AAG) construction, effective-adjacent faces recognition and complete recognition of the correlative faces, the correlative faces at all levels are recognized step by step to construct the same-side faces on both sides. Finally, the basic features and their adjacency graph are constructed by matching of the same-side unit. In order to ensure the integrity of feature faces, the definition and recognition method of fragmentary face defects in 3D part model are presented. Examples are given to illustrate the feasibility and effectiveness of the approach.