Abstract: The tensile and compressive properties of the 3D orthogonal woven carbon/epoxy composites were studied through the macro tensile and compression test, and acoustic emission (AE) analysis and SEM analysis of the fracture surface of the specimens were adopted in order to realize the failure mechanism of tensile and compression deeply. The results show that 3D orthogonal woven carbon/epoxy composites have superior mechanical performances about the tensile and compression. The damage of both tensile and compression is brittle fracture, and the main damage phenomenon of tensile is the broken and pull-out of the fiber, however, shear destruction of the fiber is the main factor of compression damage. Through the acoustic emission parameter analysis, the types of damage can be determined in the process of destruction.