Abstract: The mathematical model of a shape memory alloy (SMA) hybrid composite beam is presented. This model has been developed based on the one-dimensional SMA constitutive equation, a multicell model, theTimoshenko beam theory as well as the martensitic phase transformation of the SMA fibers embedded in the hybrid composite beam. The objective is to further understand the vibration control of the SMA hybrid composite beams. The SMA fibers are used as actuators, which are capable of changing their elastic modulus and recovery stress, thus changing the natural frequency of the vibrating beam. The effects of SMA fiber volume ratio, fiber orientation and transverse shear deformation are investigated. Numerical results show that the SMA fibers can increase the free vibration frequencies significantly.