The present study focuses on the experimental and analytical analysis of the deformability behaviour of the triaxial braided fabrics during forming. The mechanical model of the yarns based on the parameters of the reinforcements and the forming process was discussed. On the other hand, the geometric model related to the braiding angle was proposed to describe the yarns and the reinforcement deformations and to predict the yarns sliding. From the geometric model, the in-plane shearing and the material draw-in could also be predicted with respect to its magnitude and location on the braided fabric. It is clearly deduced from this study that the variation of deformability behaviours is directly impacted by the braiding angle, which is the crucial parameter for the braided fabrics.