The door leaf driving mechanism for automatic door includes frame, motor setting on the frame, transmission mechanism and door leaf suspender. It features that the frame is made of shapes with T-shaped cross section and has bent bottom in the vertical edges used as tracks, the door leaf suspender beside the bent part has pulley rolling on the tracks; and the motor and the transmission mechainsm are on the other side of the vertical edge. The door leaf suspender is connected to the reciprocating part in the transmission mechanism and has bottom connected to the door leaf. Compared with available technology, the present invention has reasonable position of door leaf suspender, reduced vertical size, compact door leaf driving mechanism and more door leaf installing space. |