Environmental factors include biological, physicochemical and psychological factors, including infection with pathogenic viruses in early pregnancy, including cold and flu viruses, varicella zoster virus, etc. Of course, mothers with immune diseases and diabetes are also prone to give birth to children with microtia. The use of hormones, sulfonamides, some herbal medicines, antiviral drugs and antibiotics such as gentamicin, streptomycin, tetracycline and leucomycin in early pregnancy can lead to the occurrence of the disease. Mental stimulation is also one of the triggering factors. Genetic factors also play an important role, as the family line is an important resource for studying the genetic factors of congenital microtia. There were seven cases in five generations of families, suggesting autosomal dominant inheritance with different phenotypes and low ectopic rates. A large survey of 171 cases of microtia in 96 families concluded that the disease is polygenic in nature, and in 2008, Chinese scholars reported a cluster of cases in a family where the patients were father and daughter with right-sided ear deformity and were first-degree relatives, suggesting that genetics is an important factor. The majority of congenital microtia are normal, but only a few patients have chromosomal abnormalities, including chromosome 5p deletion, 6q monosomy, 8q chromosome deletion, trisomy 18, 21 ring chromosome, 22q deletion, trisomy 22, 47XXY. In addition, chromosomal mosaicism has also been reported, including trisomy 7 mosaicism, trisomy 9 mosaicism, etc.