Arachnoid cysts are abnormal collections of cerebrospinal fluid encapsulated by the arachnoid membrane within the skull and can occur at any age, and are more common in children. Cranial CT and MRI are the best means of diagnosing arachnoid cysts. Arachnoid cysts appear on CT as localized brain fissures or enlarged brain pools that are filled with fluid and have the same density as cerebrospinal fluid. This localized cerebral fissure and cystic expansion of the brain pool is occupying and often results in localized pressure displacement of brain tissue, and in larger cysts, especially in pediatric patients, can cause localized skull thinning and expansion. There is no enhancement on CT scan after enhancement. Arachnoid cysts show long T1 and long T2 signals in MRI, which are completely consistent with cerebrospinal fluid. Because MRI is free of cranial artifacts, it can be viewed in multiple axes and shows relatively well for midline and posterior cranial fossa cysts. Arachnoid cysts should be distinguished from dermatomal cysts, epidermoid cysts, cystic tumors, cerebral penetrating malformations, and cerebral softening foci. The etiologic and pathophysiologic mechanisms of arachnoid cysts are not yet clear. Therefore, the treatment of arachnoid cysts is still controversial. Patients with asymptomatic, symptomatic, or smaller arachnoid cysts need to be followed up with periodic reviews to observe any increase in volume. Because of any surgery, complications such as postoperative infection and intracranial hemorrhage can aggravate the condition and even cause serious consequences due to rapid displacement of brain tissue caused by rapid decompression. Only a few intracranial arachnoid cysts are clinically symptomatic, so surgery is required when clinical symptoms and signs appear. Even if the symptoms are not obvious, the cyst may affect brain development by compressing adjacent brain tissue due to its continuous growth and its own occupying effect, or it may cause intracranial or subdural hemorrhage due to minor trauma. The indications for surgery include: 1) gradual increase of the cyst size with a diameter of more than 7 cm; 2) localized cranial augmentation or thinning of the cyst; 3) significant headache due to ventricular compression, midline deviation or intracranial hypertension caused by the cyst; 4) cyst with epilepsy and localization of the cyst by EEG; 5) rupture of the cyst due to trauma, etc. The basic principle of surgical treatment is to eliminate the pressure generated by the lesion, reduce its compression on the brain tissue, establish good cerebrospinal fluid traffic and promote brain tissue development. The current surgical methods for intracranial arachnoid cysts include: 1) direct craniotomy to remove the cyst wall and traffic the cyst cavity with the subarachnoid space, basal pool or ventricles; 2) cystic ventral shunt; 3) endoscopic cyst wall resection or fistulotomy. Open cyst debridement is generally effective because it is difficult to achieve total cyst wall excision during surgery and there are many postoperative comorbidities. Endoscopic cyst wall resection or fistulotomy has been used in clinical practice, and the efficacy needs further follow-up observation. Ventriculoperitoneal shunt is a better technique for treating arachnoid cysts, with the advantages of simple surgery, minimal trauma, safety, and good results. Usually, the cyst can be significantly reduced or disappeared when the CT is reviewed six months after the surgery, which is especially suitable for pediatric patients.