Surgical site infection (SSI) frequently occurs in patients with head and neck cancer (HNC) after tumor resection and can lead to death in severe cases. Moreover, there is no definitive conclusion about the risk factors of SSI. Therefore, it is of great clinical significance to study the factors affecting the SSI.The HNC patients included in this study were all from the Department of Oral and Maxillofacial Surgery of the Second Xiangya Hospital of Central South University (CSU), and these patients received surgical treatment in the department from January 2018 to December 2019. The cross tabulation with chi-squared testing and multivariate regression analysis were applied to determine the risk factors of SSI. To identify the key risk factors of SSI, the caret package was used to construct three different machine learning models to investigate important features involving 26 SSI-related risk factors.Participants were 632 HNC patients who underwent surgery in our department from January 2018 to December 2019. During the postoperative period, 82 patients suffered from SSI, and surgical site infection rate (SSIR) was about 12.97%. Multivariate logistic regression analysis shows that diabetes mellitus, primary tumor site (floor of mouth), preoperative radiotherapy, flap failure, and neck dissection (bilateral) are risk factors for SSI of HNC. Machine learning indicated that diabetes mellitus, primary tumor site (floor of mouth), and flap failure were consistently ranked the top three in the 26 SSI-related risk factors.Diabetes mellitus, primary tumor site (floor of mouth), flap failure, preoperative radiotherapy, and neck dissection (bilateral) are risk factors for SSI of HNC.© 2021. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.