The classification of polydactyly of the thumb is based on the Wassel classification of pathological anatomical abnormalities, which is divided into seven types, i.e., terminal phalanges, proximal phalanges, and metacarpals, and each deformity is divided into two types, bifurcation with bony connection and compound phalanges with articular connection, according to the degree of separation of the duplicated fingers, plus seven types of the 3-jointed thumb. Among them, type IV is the most common, accounting for 47%, type VII for 23%, and type II for 15%. This classification is concise and consistent with the pathology and anatomy.