Provided is a fold-in-half wagon, including a bottom frame (6), a front frame (2), a rear frame (3), a left side frame (4), and a right side frame (5). To fold the fold-in-half wagon, a middle portion of the bottom frame (6) is pulled upward, so that a front section (11) and a rear section (12) are folded relative to each other, a left fitting structure (21) moves upward from a lower end along a left guide structure (20), a right fitting structure (24) moves upward from a lower end along a right guide structure (23), and the front frame (2) and the rear frame (3) move toward each other and drive parallelograms of the left side frame (4) and the right side frame (5) to lift middle supporting bases.