Coupling between the magnetic field, electric field, and strain in continuum media is achieved when magneto-elastic (piezomagnetic) and electro-elastic (piezoelectric)layersare composed together to form a smart plate. A mathematical model was developed to investigate the effective properties for these three phases material when it modeled as plate for sensors and actuator devises, which construct with in-plane polarizations. The results have demonstrated that combining the piezoelectric and piezomagnetic to form two-phase smart composite improved the electro/mechanical coupling factor, if the poling axis align at 90 for (Li-Ni), and (Li-Ta), and zero for (Qu), and (La). In the other manner, the magneto/mechanical coupling factor remain constant. © 2011 IEEE.