Abstract: The center-cracked aluminum alloy plates were one-sidedly bonded with unidirectional carbon fiber/ epoxycomposite patches by the vacuum-bagging process. The tensile st rength of the bonded plate was measured , the crackpropagation , the interface disbond between the patch and the plate , and the residual tensile st rength of the bondedplates were also investigated. The result s show that both the tensile st rength and the stiffness of the center-crackedplates bonded with composite patches increase significantly. The crack propagation rate of the bonded plate is smaller than that of the cracked plate , and the fatigue life of the bonded plate is longer than that of the cracked plate.The tensile st rength and the fatigue life of the bonded plates are 364. 74 MPa and 77546 cycles , respectively , whilethose of the cracked plates are 311. 48 MPa and 32217 cycles , respectively. An elliptical debond area between thecomposite patches and cracked plate is found during the tension-tension fatigue testing. The interface debond area increases with increasing the fatigue cyclic number , and the magnitude of the increase is related with the fatigue cyclicnumber.