The shear failure mechanisms of ±45° braided and unidirectional carbon fibre reinforced polymer (CFRP) laminates are investigated. Off-axis tensile tests were carried out to determine the performance and failure modes of laminates with different numbers of layers. A mesoscale unit cell finite element model was established, and the simulation was validated. The results show that braided laminates and unidirectional laminates have different failure cracks. With the increase in the number of layers, the failure mode of laminates changes. For laminates with 8 or more layers, the necking effect appears at the fracture, and there is a fibre rotation strengthening stage in the stress–strain curve. The stress–strain response functions of laminates in the fibre rotation strengthening stage fitted according to test data can effectively reflect the properties of ±45° braided and unidirectional CFRP laminates.