This paper reports the effects of temperature and fiber architecture on the shear properties and failure mechanismof 3D MWK composites under compressive loading at room and elevated temperatures. The shear experiments of compositeswith three fiber architectures were performed at five different temperatures. Macro-fracture and SEM micrographs wereexamined to understand the deformation and shear failure mechanism. The results show that shear stress-strain curves shownon-linearity and plastic fracture feature, and exhibit plastic platform at elevated temperatures. The temperature hassignificant effects on the shear properties which decrease significantly with increasing the temperature due to degradation ofmatrix properties, especially after 75 oC. The shear properties can be affected greatly by the fiber architecture and theseincrease significantly with the increase of 45 o direction fiber at different temperatures. The results also show that the damageand failure patterns of composites vary with the fiber architecture and temperature. At room temperature, the interfacialadhesion between fibers and matrix is high, the local delaminating and shear failure feature are prominent. At elevatedtemperatures, the composites become more softened, cracked and attain plasticity. The damage of matrix plastic andcracking, interface debonding, and fiber layer delaminating change significantly.