A left-sided subventricular cyst is a small cyst-like change beneath the anterior horn and body of the lateral ventricle under the ventricle. The causes of left-sided subventricular cysts can be categorized as congenital or acquired. Congenital is due to intrauterine infection, usually seen in preterm infants, associated with poor development of the embryonic developmental layer in preterm infants, and usually disappears gradually in the first 2 to 4 weeks of life. If the cyst is not absorbed for more than 6 months, and the cyst gradually increases in size to >15mm, it will compress the surrounding brain tissue, and then surgical intervention and treatment should be actively carried out. It is recommended to go to the hospital in time if abnormalities occur, and actively cooperate with the relevant examinations and treatments under the guidance of the physician, so as to avoid delaying the condition.