Folding stool

A folding stool, comprising a seat portion (1) and a backrest (2), the backrest (2) consisting of a soft surface layer and a hard sandwich board wrapped in the soft surface layer, the seat portion (1) being a cuboid, and both an upper surface and four side surfaces of the cuboid consisting of the soft surface layer and the hard sandwich board wrapped in the soft surface layer;

• wherein, a first hard sandwich board (201) in the backrest (2) is connected to a second hard sandwich board (101) under the upper surface of the seat portion (1) via a hinge device, the hinge device comprises a first hinge (3) and a second hinge (4) that are connected to each other rotatably, two first hinges (3) are respectively fixed on the second hard sandwich board (101) and the first hard sandwich board (201), the first hinge (3) comprises two ear portions provided along a longitudinal direction, the second hinge (4) comprises four ear portions provided symmetrically along the longitudinal direction and a transverse direction, two ear portions of the first hinge (3) on the second hard sandwich board (101) are connected to two ear portions provided along the longitudinal direction and located at a same side of the second hinge (4) by means of a rotary shaft (5), two ear portions of the first hinge (3) on the first hard sandwich board (201) are connected to the other two ear portions provided along the longitudinal direction of the second hinge (4) by means of another rotary shaft (5), a position limiting board (6) is fixed on a back surface of the second hinge (4), the position limiting board (6) comprises two longitudinal position limiting surfaces (601) opposite to each other, when the backrest (2) is rotated to be perpendicular to the upper surface of the seat portion (1) via the hinge device, the two longitudinal position limiting surfaces (601) of the position limiting board (6) are respectively used to limit the rotation of the second hinge (4) and the first hinge (3) on the first hard sandwich board (201), the first hinge (3) is a groove structure, the two ear portions are defined on two side walls (301) of the groove structure and are defined on end portions of the two side walls (301), a bottom of the groove structure is a connection portion (302), connection portions (302) of two first hinges (3) are respectively fixed to the second hard sandwich board (101) and the first hard sandwich board (201), and an end surface (303) of the groove structure located at a same side with the two ear portions are arranged correspondingly to the longitudinal position limiting surface (601) on the position limiting board (6).