The invention discloses a folding chair. The folding chair comprises a chair surface, chair legs and a backrest. The main structure of the folding chair is as follows: a backrest frame is hinged with the rear end of a supporting frame by a hinging shaft, the lower end of the backrest frame is provided with clamping hooks and the upper parts of front legs are provided with clamping hook sleeves matched with the clamping hooks; the front chair legs and rear chair legs are hinged at the middle positions in an intersecting manner, the upper ends of the front chair legs are hinged with the rear end of a hinging connection plate arranged at the lower surface of the chair surface, the upper ends of the rear legs are hinged with one end of a connecting rod, and the other end of the connecting rod is hinged with the middle part of the hinging connection plate; and an upper cross rod is arranged between the upper ends of the two rear legs, a manual clamping lock is arranged on the lower surface of the chair surface, and a clamping-lock concave hole is formed in the position of the upper cross rod corresponding to the manual clamping lock. The folding chair disclosed by the invention has the advantages that not only can the chair surface, the chair legs and the backrest be folded and stand, but also the whole body can be refolded downwards to reduce the height; and when the chair is in use, the front legs and the rear legs are supported on the four corners of the chair surface, the chair surface and the chair legs are closely combined, and due to the backrest frame, the problem of excessive inclination is avoided, so that the folding chair is convenient to carry and store, firm in structure, uniform in stressing and comfortable in use.