Open craniosynostosis or firearm penetrating injuries, irreducible comminuted or depressed fractures after reopening, severe craniosynostosis patients after debridement and decompression, and pediatric skull fractures can all result in large cranial defects. Usually, skull defects less than 3 cm are asymptomatic, and after temporal muscle decompression or suboccipital decompression, there are thick muscles and fascia covering and forming tough fibrous healing layer in the defect area, which can play the role of the original skull to protect the brain, and there is no symptom in the clinic. Defects with a diameter of more than 3 cm, especially those located in the frontal area, which are an obstacle to beauty and safety, often have one or another symptoms, such as dizziness, headache, local tenderness, irritability, restlessness, or patients are afraid of the pulsation, expansion, collapse of the defect area, fear of the sun, fear of vibration and even fear of loud noises, often have poor self-control, concentration and memory loss, or have depression, fatigue, reticence and low self-esteem. The patient’s head is seriously deformed due to large skull loss, which directly affects the physiological balance of intracranial pressure, collapses when upright, expands when lying down, concave in the morning and convex at night, or the atmospheric pressure acts directly on the brain tissue through the defect area, which inevitably leads to local brain atrophy over time and aggravates the symptoms of brain wasting, and at the same time, the affected ventricle gradually expands and expands or deforms into the defect area. What is the differential diagnosis of cranial defects? Differential diagnosis of giant cranial defect: the typical local clinical manifestations of the defect, combined with X-ray plain film and CT scan, can make a clear diagnosis. The main points of diagnosis are the skull defect and the contents herniated out of the cranial cavity through the defect, and the diagnosis is not difficult. For meningeal bulge or meningoencephalic bulge at the base of the skull, it should be considered to be differentiated from nasal polyps or pharyngeal tumors, but the diagnosis can still be made clearly under the three-dimensional observation of MRI. Nasal polyp: It is a common disease of the nose and is also associated with certain systemic diseases. It is the result of tissue edema caused by long-term inflammatory reaction of nasal mucosa. Pharyngeal tumors: The pharynx is divided into nasopharynx, oropharynx and hypopharynx, and tonsils are listed as a separate part. The incidence of squamous cell carcinoma is high among pharyngeal tumors, and the incidence of squamous cell carcinoma is still high among the tumor types of nasopharynx, oropharynx, and hypopharynx, while the incidence of malignant lymphoma is higher than that of squamous cell carcinoma in tonsil tissue, with squamous cell carcinoma taking the second place. Squamous cell carcinoma, malignant lymphoma, fibrovascular tumor and pleomorphic adenoma are the main tumor types, and the vast majority of pharyngeal tumors occur in the nasopharynx. Malignant lymphoma is mainly concentrated in the tonsils. Through the above diagnosis, we understand that cranial defects can have adverse effects on patients, so it is recommended that patients who need early cranial repair should have early cranial repair once contraindications to cranial repair are excluded.