Objective: To investigate the diagnosis, surgical treatment and prognostic factors of primary malignant tumors of the duodenum. Methods: The clinical data of 88 patients with primary malignant duodenal tumors treated during January 2008 to December 2015 were analyzed retrospectively. Results: Of the patients, the tumors in 5 cases located in the duodenal bulb, in 69 cases located in the descending portion, in 9 cases located in the horizontal portion and 5 cases located in the ascending portion, and among them, the tumors in 62 cases located within the duodenal papilla area of descending part, which accounted for 89.86% of those in the descending portion; the tumor types were classified as adenocarcinoma in 56 cases (63.64%), malignant stromal tumor in 20 cases (22.73%), carcinoid tumor in 6 cases (6.82%) and other tumors in 6 cases (6.82%); the histological types were divided into well differentiated in 34 cases (38.63%), moderately differentiated in 28 cases (31.82%), poorly differentiated in 19 cases (21.59%) and undifferentiated in 7 cases (7.95%). Clinical manifestations of the patients included abdominal pain, abdominal distention, jaundice, vomiting and upper gastrointestinal hemorrhage, which showed no specificity. The preoperative correct diagnosis rate by endoscopy, hypotonic duodenograph, ultrasound and CT was 83.54% (66/79), 80.00% (20/25), 30.56% (11/36) and 47.72% (42/88) respectively. Sixty patients underwent pancreaticoduodenectomy, 8 patients received segmental duodenectomy, and 5 cases were subjected to subtotal gastrectomy plus duodenal bulb resection and 15 patients had palliative bypass surgery. The overall 1-, 3-, and 5-year survival rate for the whole group of patients was 82.34%, 54.79%, and 28.98% respectively, and for patients receiving pancreaticoduodenectomy was 100%, 68.12%, 42.04% and for those undergoing segmental duodenectomy was 100%, 61.96% and 0; the postoperative survival time of patients after palliative bypass surgery was 6 to 24 months; the survival rate in patients with duodenal stromal tumors was significantly higher than that in patients with duodenal adenocarcinoma (χ2=7.237, P=0.007). Univariate analysis showed that depth of tumor invasion, tumor differentiation, lymphatic involvement and surgery type were significantly related to the postoperative survival of the patients (all P<0.05); multivariate analysis revealed that depth of tumor invasion, lymphatic involvement and surgery type were independent factors for the prognosis of the patients (all P<0.05). Conclusion: Primary malignant duodenal tumors frequently occur in peripapilla area of descending duodenum and mainly are adenocarcinoma, for which, duodenoscopy and hypotonic duodenograph are the major diagnostic methods, and pancreaticoduodenectomy is the first choice of treatment.