The invention discloses a folding chair, comprising a square base and a movable chair back, wherein the square base consists of a square plate (3) and chair legs (1) at four corners of the square plate (3), the movable chair back consists of a chair back body (5) as long as the chair legs (1) and a movable plate (4) consistent with the square plate (3) in shape, an angle of 90 degrees is formed between the movable plate (4) and the chair back body (5), and the movable plate (4) is connected with the front end of the square plate (3) through a movable shaft (2). As the chair is folding, the upper layer of the chair can be laid down while the chair back is supported on the ground as needed so as to form a bar table structure. The folding chair is simple in structure and convenient to use.