This chapter contributed towards understanding the deformability characteristics of braided fabric that can be considered as a comparable substitute for woven one in multilayers stacking process before preforming reinforcements with desired shapes. The corresponding braiding machinery, process, and its braiding patterns were introduced firstly. The in-plane shearing behavior, which is much correlated with braiding patterns’ characters determining the deformability of braided fabrics, was then presented for building a bridge to realize how it is important for preforming process and why it can be designed closely to braiding angle that can be obtained by setting the appropriate braiding parameters. At last, the deformability of braided fabric, a definition to evaluate the deforming behaviors including shearing, sliding, and material draw, was discussed utilizing the experimental and theoretical analysis. It can be confirmed that the deformability can be well quantitatively predicted by the combination models including characters of braided fabrics and preforming shape.