Objective: To investigate the clinical features, histopathological and immunohistochemical staining characteristics of adrenal cortical carcinoma (ACC), and to evaluate the predictive value of prognosis based on pathological features. Methods: The clinicopathological features of 22 ACC patients admitted to the First Affiliated hospital of Xi’an Jiaotong University from January 2010 to December 2018 were retrospectively analyzed. Results: All tumors were irregularly shaped, vwith necrosis 14 cases had capsular invasion and 10 had calcification. The Weiss scores of all cases were ≥3. Immunohistochemical results showed Ki-67 index varied from 5% to 70%. Eighteen cases were Vimentin (Vim) positive, 16 were synaptophysin (Syn) positive and 9 were MelanA positive. Inhibin, CR, NSE and CD34 were positive in 8, 10, 10 and 8 cases respectively. Six cases were CK positive and 1 was CgA positive. The Ki-67 index in cases with distant metastasis were significantly higher than that in cases without distant metastasis [(28.83±8.95)% vs (10.91±2.41)%, P=0.025]. ROC curve was used to analyze the power of Ki-67 index in predicting distant metastasis. The area under the ROC curve of end-stage patients was 0.86 (P=0.03). A cut-off value of 6.5% resulted in sensitivity of 100% and specificity of 50%. The sensitivity and specificity were both 80% when using a cut-off value of 12.5%. Kaplan-Meier survival curve was used to evaluate prognosis. Patients undergoing adrenal tumor resection had a significantly better long-term outcome than those without resection (Median survival 30 months vs 8 months, P=0.006). For patients receiving standardized treatment recommended by the NCCN guideline, patients with Ki-67 index < 20% had a higher median survival than those with Ki-67 index ≥20% (50 months vs 6 months, P=0.011). Conclusion: Pathological examination is the gold standard for ACC diagnosis. Ki-67 index is significantly higher in patients with distant metastasis and can be used to predict the prognosis of late stage ACC.