Congenital microcephaly, also known as true microcephaly or autosomal recessive primary microcephaly (MCPH), is a neurodevelopmental disorder. Its main clinical feature is a reduction in head circumference accompanied by a degree of non-progressive mental deterioration. The etiology of microcephaly includes environmental, genetic and infectious factors. It is generally accepted that MCPH is a polygenic, invisible disorder. The reported incidence varies widely throughout the world, with the highest incidence in northern Pakistan and some Asian countries where consanguineous marriage is prevalent and a lower incidence in northern European countries. The morphological description of microcephaly dates back more than a century, with Giacomini first describing the basic features of microcephaly in the literature in 1885, and its name has changed in a large number of literature reports as the understanding of microcephaly has grown. The initial morphologic descriptive designation gradually changed to a genetic etiologic name. In 1959, Van Den Bosch adopted the diagnostic name of primary microcephaly based on morphology, referring mainly to the independent, non-syndromic microcephaly. In 1964, Kloepfer considered primary microcephaly as a chromosomal recessive disorder and distinguished it from other causes (such as trauma, infection, and other acquired factors) of microcephaly as true microcephaly. The development of the brain includes fetal stage and postnatal stage. MCPH mainly affects the development of the brain in the fetal stage, and the head circumference measurement and brain volume of the affected child can be found to be lower than normal fetuses of the same age by applying ultrasound technology and MRI scan at about 24 weeks of gestation. Head circumference measurement after birth is one of the most common ways to diagnose microcephaly, and it is often used clinically as a criterion to diagnose microcephaly by 3 standard deviations less than the normal head circumference of children of the same age. The presence of moderate-to-mild mental deterioration is also an important adjunct to the diagnosis. MCPH is a congenital microcephaly that excludes secondary factors and is also characterized by a degree of microcephaly that does not vary with growth and development. Patients’ CT and MRI imaging often suggest that the structure of the brain is basically normal while the cortical development is significantly underdeveloped, and the height, weight, and appearance are mostly normal. Most patients with MCPH show a moderate lag in intellectual development and delayed language development in the first year of life. Subsequent development is observed to be extremely active and may be accompanied by neurological deficits such as aggressive behavior, low attention span and seizures. Patients with MCPH can acquire some basic life skills through acquired learning. In addition, most patients with MPCH have non-specific frontal anterior tilt symptoms. However, this symptom is not present in all patients with MPCH.