The folding wing is one of the most promising plans for designing a morphing aircraft. The aerodynamic and oscillatory characteristics of the aircraft will change as its wings fold. In order to investigate the vibration of the folding wings of a morphing aircraft, a structure with folding plates was designed and made. A method for constructing mechanical models for complicated structures was introduced. Mode shapes of low frequencies were experimentally obtained to discretize the structure with folding plates. And possible internal resonant frequencies of the system were studied.