Objective To investigate the clinical manifestations, diagnostics, and treatment of chylothorax following neck dissection for oral cancer. Methods The clinical data of 3 patients with chylothorax after neck dissection for oral cancer from January 2020 to May 2021 in the Stomatological Center of Xiangya Hospital, Central South University, were retrospectively analyzed in detail, and the relevant literature was reviewed. The risk factors, clinical manifestations, diagnostics, treatment, and prognosis of chylothorax were summarized. Results The 3 patients were all male patients with oral cancer aged 42-63 years. Their clinical manifestations were progressive dyspnea 2-5 days after cervical lymphadenectomy. Chest X-ray, B-ultrasound, and/or CT showed unilateral or bilateral pleural effusion, and the diagnosis was confirmed after a positive chylous test of pleural puncture fluid. There was 1 case with left chylothorax (1 case after left neck dissection) and 2 cases with bilateral chylothorax (1 case after left neck dissection, 1 case after bilateral neck dissection). Severe neck chylous leakage occurred in 2 patients; local compression did not work, and the thoracic ducts were ligated. All patients were treated with nutritional support, assisted mechanical ventilation, tube thoracostomy drainage, and other conservative treatments. The chylothorax volume of each patient was gradually reduced, and the chest drainage tube was removed 7 to 15 days later. All patients recovered successfully. The literature review results showed that when patients with oral cancer after neck dissection experienced progressive dyspnea, related auxiliary examination methods such as chest X-ray, B-ultrasound, CT, and chyle tests should be used by clinicians. When a patient is diagnosed with chylothorax, they should be treated with nutritional support, mechanical ventilation, somatostatin, thoracic puncture drainage, other conservative treatments, and even thoracotomy and ligation of the thoracic duct surgery when necessary. Conclusion Chylothorax is a relatively rare complication after neck dissection for oral cancer. It mainly occurs bilaterally or only in the ipsilateral pleural cavity on the surgical side of neck dissection. Left neck dissection is a risk factor. The clinical manifestations are mostly progressive dyspnea after neck dissection. Detailed physical examination, chest X-ray, B ultrasound, and/or CT could detect pleural effusion, and chylothorax could be diagnosed when milky white or pale yellow chylous liquid is aspirated and the chylous test is positive. Most patients can be cured with tube thoracostomy drainage, respiratory support, and other conservative treatments.