A foldable wagon comprises a foldable frame, a pull rod assembly installed at the front of the foldable frame, and walking wheels installed at the bottom of the foldable frame, wherein the foldable frame comprises an underframe, a front frame arranged at the front of the underframe, a rear frame arranged at the rear of the underframe, and side frames arranged at the left and right sides of the underframe; and the underframe is connected with the front frame, the rear frame, and the side frames through a lower connecting seat, a supporting rod, and an upper connecting seat to form a foldable frame structure; the underframe comprises a bottom beam and side rods arranged at the front and rear sides of the bottom beam in a crossed manner, which form a stable triangular support structure in a crossed manner; the structural strength of the bottom is high, and the bottom beam comprises a fastening member. The fastening member is connected with the overlapping joint of two inner long rods of the inner rod of the side frame by a bolt penetrating way, which realizes the interconnection between the underframe and the side frame and further increases the overall strength of the foldable frame.