The previous kinematic model used to describe the in-plane shearing behaviour of biaxial fabrics in Bias-Extension Test (BET) has a deficiency in which the transverse deformation of yarns is ignored during the yarns compacting phase, making it impossible to precisely calculate the in-plane shear force. This paper not only demonstrated the accuracy of previous kinematic model merely suitable for the relative looser fabrics before the yarns compact, but also proposed a revised kinematic model considering the variation of yarn width to better understand the in-plane shearing behaviour during the yarns compacting. The BET results, which were obtained using two fabrics manufactured from completely different yarns, clearly show that the revised model could provide more credible data in calculating the variation of in-plane shear angle and force than the previous model. In addition, the yarns compacting stress was also studied to understand the transition from yarns compacting to slippage during BET.