The invention discloses a folding chair. The folding chair comprises a folding chair main body and a seat cushion; the folding chair main body comprises a main body base, a support leg group, multipletelescopic positioning rods and a locking mechanism; the support leg group comprises multiple support legs which are pivoted to the outer periphery of the main body base and unfolded downwards relative to the main body base so as to form a support for the main body base or folded upwards together relative to the main body base, a containing groove is formed in the front face of each support leg,and the upper end of each support leg is linked; the lower ends of the telescopic positioning rods are pivoted to the upper ends of the containing grooves, and can unfold upwards or be accommodated inthe containing grooves relative to the supporting legs; the upper ends of the telescopic positioning rods are connected with the seat cushion, and can unfold and support the seat cushion; the lockingmechanism comprises a positioning frame installed in an inner cavity of the main body base, an unlocking key which is inserted into the positioning frame and fixed to the positioning frame and a spring arranged between the unlocking key and the main body base; when the supporting legs are unfolded downwards relative to the main body base, a locking block on the outer side of the positioning frameis clamped in a positioning groove formed in the upper end of each supporting leg, and positioning is conducted under the elastic force of the spring.