A transmission structure disposed in an input device of a data processing system is disclosed. The transmission structure includes a fixed plate, a movable plate, a connection member, and a motor driving unit. The fixed plate is mounted in the input device and includes a set of grooves extending toward a first direction. The movable plate is movably disposed on a first surface of the fixed plate and includes a set of first pillars to be disposed in the set of grooves. The connection member is connected to the movable plate. The motor driving unit is connected to the connection member and drives the movable plate through the connection member to move toward the first direction or a second direction opposite to the first direction.