The invention relates to sliding plug door bearing mechanism; wherein a bearing trolley, an upper connecting shaft, an upper hinge seat and a door-carrying support are sequentially connected to form a turning pair I; the door-carrying support, a lower connecting shaft, a lower hinge seat and door leaf are sequentially connected to form a turning pair II; a bearing wheel and a bearing guide rail are connected to form a sliding pair I; a guide slideway and a guide wheel are connected to form a sliding pair II in preset track; the bearing trolley does X axial translational motion along the bearing guide rail while the door-carrying support drives the door leaf to rotate around the X axis of the bearing trolley; and the door-carrying support does linear motion along the bearing guide rail while rotating around the X axis on the bearing trolley, and the door-carrying support drives the door leaf to shift along Y axis direction of the door leaf according to the track of the guide slideway. The invention has the advantage that translational motion of the bearing guide mechanism of the door leaf along X axis direction and rotation around the X axis realize shift of door leaf along Y axis direction. Translational motion and rotation are integrated on one bearing guide mechanism, structure is compact, reliability is high, and parts processing is low in processing precision, good in performance and low in manufacturing cost.