Microtia, or congenital malformation of the external and middle ear, is characterized by hypoplasia, atresia or stenosis of the external auditory canal, and malformation of the middle ear, while the inner ear is mostly normal in development and has some hearing through bone conduction. During the developmental stage of the auricle, the embryo is susceptible to a variety of developmental malformations of the auricle due to genetic or external factors. Congenital microtia can occur alone or as part of a syndrome. The common syndromes are Treacher Collins syndrome, Goldenhar syndrome, Nagar syndrome, and Miller syndrome. According to the degree of deformity, the most common clinical classification of microtia is three types: degree I: the size and shape of the auricle changes, but the important surface structures of the auricle exist, the external auditory canal is narrowed, and in severe cases, the external auditory canal is atretic; degree II: the most typical, only the vertically oriented ear wheel exists, and the external auditory canal is atretic; degree III: only the skin and cartilage masses remain, and in severe cases, there is no ear. This is the most common type. In layman’s terms, microtia is a small ear, in the broad sense that one side of the ear is smaller than the other. The purpose of typing and grading from clinical manifestations is to facilitate classification and treatment.