A seat back linking mechanism includes a base frame having a pivot portion; a back frame pivotally connected to the base frame; an actuation member slidably coupled to the back frame; a linkage having a first link and a second link pivotally coupled together, the first link and the second link being respectively pivotally coupled to the pivot portion of the base frame and the actuation member, and a driven slot; and a drag member having a drag pin adapted for dragging the driven slot of the linkage.