During high-speed and high-precision motion of a gantry platform driven by dual permanent magnet linear synchronous motor (PMLSM), large dynamic synchronization errors are prone to occur due to the difference in dynamic responses between the two motors and the mechanical coupling effect of the crossbeam. Under the constraints of the linear guideways, these errors generate excessive mechanical stress and additional friction losses, severely affecting the motion accuracy and service life of the platform. Moreover, the motion state of the beam mover directly influences the dynamic response of the dual-PMLSM displacement tracking control, ultimately affecting the dynamic synchronization error of the dual PMLSM movers. To address these issues, this article first establishes the dynamic equations of the dual-PMLSM-driven gantry system and reveals the principle by which the beam mover position and its dynamic motion along the crossbeam affect the beam deflection motion. Then, based on the composite displacement error, a cross-coupled sliding mode synchronous control for the dual PMLSM movers is constructed. To mitigate the adverse effect caused by the continuously changing center of mass of the beam during its motion on synchronization suppression, the dynamic model is combined with the real-time position of the beam mover to perform current reconstruction, thereby reducing the dynamic synchronous displacement error. To overcome the control lag problem inherent in traditional fuzzy control that uses error as the feedback core, the net q-axis current of the beam mover, which is directly related to the beam torsion torque, is adopted in the fuzzy control. Taking the net q-axis current of the beam mover as the dominant factor, a fuzzy variable-gain control strategy is constructed by also incorporating the synchronous displacement error and synchronous velocity error of the dual PMLSM movers, so as to further reduce the influence of the beam mover′s dynamic motion along the beam on the dynamic synchronous displacement error. Experimental results show that, compared with the cross-coupled sliding mode synchronous control with constant gains, the proposed control strategy achieves a substantial reduction in the peak synchronization error during both the start-stop processes of the dual PMLSMs and the crossbeam mover.