In a multi-axis metal hybrid layered manufacturing system, a combined laser material deposition and material removal system with more than 3-aixs mobility, sometimes support structures are necessary in the part building process, which prevent object from falling during deposition process. Since the support material is the same as build material, it is very difficult to remove the support material in the post processing stage. Thus, the support material must be machined off. Therefore, the geometry information of support structures is important for the machining process. In this paper, a method is presented to extract support structures automatically. Two types of support structures, trapped and non-trapped, are classified in this paper and their extraction methods are discussed respectively.