Objective: To investigate the factors affecting the postoperative swallowing dysfunction in patients who underwent oral cancer surgery. Methods: Retrospective review of clinical records of 70 patients (50 males and 20 females) who underwent oral cancer surgeries from July 2007 to April 2015 were enrolled. Multiple regression analysis was performed using the Food Intake LEVEL Scale (FILS) at discharge as the objective variable and age, tumor size, resection of the tongue base, suprahyoid muscle resection, segmental mandibulectomy, neck dissection and radiation therapy as the explanatory variables in 70 patients. In addition, multiple regression analysis was performed between objective variables, which include maximum hyoid bone movement, laryngeal elevation delay time, pharyngeal constriction ratio (PCR), residue in the vallecular and pear-shaped depression (pyriform sinuses), and Penetration-Aspiration Scale score and one of the main factors representing the characteristics of each case as the explanatory variables, and age was treated as an adjustment factor in 23 patients. Results: The FILS shows significant negative correlation by age and resection of the tongue base. In videofluoroscopic swallowing study, the maximum movement, PCR and residue in the vallecular are significantly correlated with factors demonstrating the characteristic for each case. Conclusion It was suggested that in elderly patients, the presence of more than half of the tongue base resection, suprahyoid muscle resection and neck dissection cause severe dysphagia after surgery.