Objective: To investigate the expression of trophoblast cell-surface antigen 2 (TROP2) in salivary adenoid cystic carcinoma (SACC) in order to analyze its relationship with TROP2 expression and clinicopathological features, as well as to clarify the correlation between TROP2 expression and the prognosis of patients with SACC. Methods: With approval from the ethics committee, the expression of TROP2 in 85 SACC and paracancer tissue samples was detected by using the immunohistochemical method, and the relationship between TROP2 expression and clinicopathological characteristics was analyzed. The Kaplan-Meier method was used to analyze the relationship between TROP2 protein expression and 5-year disease-free survival (DFS) in 40 patients with SACC. Furthermore, the logistic regression model was used to analyze the prognostic factors of patients with SACC. Results: The low or no expression rate of TROP2 in SACC tissues was significantly higher than that in paracancer tissues (P<0.001). Low or no expression of TROP2 was significantly positively correlated with tumor growth and clinical staging in patients with SACC (P<0.05). Kaplan-Meier survival analysis showed that the DFS of patients with SACC with low or no expression of TROP2 protein was significantly lower than those of patients with high expression of TROP2 protein (P<0.05), and the prognosis was poor. The logistic regression model showed that low or no expression of TROP2 protein (OR = 5.37; 95% CI: 1.03-28.08; P = 0.046) and Ⅲ-Ⅳ clinical staging (OR = 6.89; 95%CI: 1.37~34.77; P = 0.019) were risk factors affecting the prognosis of patients with SACC. Conclusion Low or no expression of TROP2 protein in SACC tissues leads to poor prognosis of patients and is positively correlated with tumor growth and clinical staging. In addition, low or no expression of TROP2 can be used as an independent prognostic risk factor for poor prognosis in patients with SACC, and TROP2 is a marker of poor prognosis in patients with SACC.