Abstract: The energy method is used to analyze the transverse vibration of simply-supported stiffened rectangular plates with a single crack stiffener. The rectangular plate and the stiffener are cut along the interface， and then the stiffener is divided into several sub blocks along the crack. The energy equations of the transverse vibration of the rectangular plate and each sub blocks are ob tained by using the thin plate model and the plane stress theory. The displacement functions of rectangular plates and sub blocks are constructed by using the first kind of Chebyshev polynomials. The transverse vibration characteristic equation of a stiffened rectan gular plate with a single cracked stiffener is obtained by the Ritz method and plate-stiffener displacement continuity condition. Finally， the effects of crack depth and crack position on the dimensionless frequency are analyzed.