A foldable chair includes a seat plate, two X-shaped supporting frames symmetrically, and two sliding connecting members, each of the two X-shaped supporting frames includes a front leg and a rear leg pivotally connected together, the front leg and the rear leg are located outside of the seat plate, the rear leg is disposed between a side edge of the seat plate and the front leg, an upper end of the rear leg is pivotally connected to a front position of the side edge of the seat plate, each of the two sliding connecting members includes a sliding part, a fixed part, and a positioning plate, and the positioning plate is located on a rear side of the front leg, so that the rear leg is configured to abut the positioning plate and align with the front leg in a left-and-right direction after the foldable chair is folded.