Mechanic performances of the textile reinforcements and composites depend strongly on their reinforcement structure, which plays an important role during the composite manufacturing and in-service life of the composite materials. By contrast with woven reinforcements, the braided fabrics are also widely used as textile reinforcements to manufacture the advanced composite parts. After cutting and opening stages, the braided fabrics can be used as two-dimensional reinforcements, which present an interesting structure: non-orthogonally structure. To improve the understanding of this promising composite reinforcement, in particular, their mechanical behavior, this chapter will explain in details the braided structures and their important mechanical characterizations. The influences and the link between the mechanical properties and the fabric structure will be summarized. Moreover, the forming behaivor of the braided fabrics during the manufacturing will be also described.