In order to measure the mechanical property of architectural fabrics, a test method of biaxial shear test was used. The biaxial shear tests for four kinds of architectural fabrics were carried out, then the shear stress strain curves, shear modulus, residual shear strains and hysteresis loop area were obtained. The analysis results show that the plastic shear deformation of G type fabric is notable, but the shear deformation of P type fabric is mainly elastic at the first cycle of each stress stage. The linear feature of the load rising segment of shear stress strain curves enhances and loading slope increases gradually with the increase of the number of cycles. The residual shear strains, hysteresis loop area and loading slope are different when the direction of shear stress is changed. The shear modulus calculated by considering the all cycles are smaller than those calculated only considering the last cycle of each stress stage. The sequence of shear modulus of fabrics is FGT 800>FGT 600>F 1202>F 1002.