Objective : To explore the prognostic value of chemoradiotherapy based on the depth of invasion (DOI) in patients with oral squamous cell carcinoma. Methods : Patients with oral squamous cell carcinoma who received surgical treatment in a hospital from 2008 to 2016 were enrolled. The chi-square test was used to compare the effects of DOI on postoperative cervical lymph node metastasis and local recurrence. The effects of chemoradiotherapy on postoperative cervical lymph node metastasis, local recurrence, and survival were analyzed based on the DOI. Results: A total of 111 patients with oral squamous cell carcinoma were included in this study. The postoperative local recurrence rate (P<0.05) and cervical lymph node metastasis rate (P<0.05) of patients with 5 mm < DOI ≤ 10 mm and DOI > 10 mm were significantly higher than those with DOI ≤ 5 mm. The time of postoperative recurrence was concentrated within two years after the operation. The greater the DOI was, the shorter the time to postoperative recurrence (P<0.05). The addition of postoperative chemoradiotherapy did not significantly improve the postoperative local recurrence rate, cervical lymph node metastasis or survival rate of patients with different DOIs (P > 0.05). Conclusion DOI has important predictive value for postoperative recurrence, cervical lymph node metastasis and survival rate. However, DOI cannot be used as an independent index to guide whether chemoradiotherapy is needed after oral cancer surgery.