Congenital hooked thumb is a type of congenital thumb hypoplasia, which can be divided into four types depending on the severity of the developmental disorder. Type I: extension disorder only; Type II: extension disorder with flexion contracture or tiger’s mouth contracture; Type III: with thumb hypoplasia, including muscle and tendon hypoplasia; Type IV: other deformities that do not belong to the above three categories. Treatment: Type I: reconstruction of the thumb extensor function by transplantation of the intrinsic extensor, radial carpal extensor and palmaris longus tendon; Type II: reconstruction of the thumb extensor function by transplantation of the intrinsic extensor, radial carpal extensor and palmaris longus tendon, in addition to the same as type I. The skin of the tiger’s mouth should be released, and if necessary, the thumb retractor stop and the thumb short flexor tendon stop should be partially severed and the joint capsule on the palmar side should be released. Type III: Based on the treatment of type I and II, the corresponding functional reconstruction is done according to the incomplete development of the thumb muscles and tendons. Type IV: Other deformities are treated accordingly. Typical case: Child, female, 5 years old, 5 years old, metacarpophalangeal joint extension disorder of both thumbs Preoperatively, unfortunately, the picture of the left thumb might have been mistakenly deleted, but the situation was the same as that of the right hand, because the metacarpophalangeal joint could not be dorsally extended and the interphalangeal joint was compensated for hyperextension, making the appearance of the thumb like a hook. Bilateral transposition of the intrinsic extensor tendons of the index finger, palmar skin release, and full-thickness skin grafting were performed. After removal of one extensor tendon from the index finger, the extensor function was not affected and the dorsal extension of the thumb was completely normalized.