Objective To investigate the clinicopathological characteristics, diagnosis and treatment of primary duodenal malignant tumors (PDMTs). Methods The clinical data of 47 PDMTs confirmed by pathology were retrospectively analyzed. Results Pathological types were adenocarcinoma in 42 cases, leiomyosarcoma in 4, and carcinoid in 1.The most common location of the tumor was the descending portion (35), especially the peri-papillary region (28) of the duodenum. The most common symptoms and signs were abdominal pain, jaundice, upper gastrointestinal hemorrhage, obstruction ,and weight loss. The main diagnostic modalities were gastroduodenoscopy, GI barium meal, ERCP, ultrasound (US) and CT. US together with ERCP was the most useful in improving the diagnosis of peripapilla tumors in the duodenum. Panceraticoduodenectomy and some palliative procedures were performed for 25 and 20 cases, respectively.Surgical mortality and postoperative morbidity were 2.2% (1/45) and 20% (9/45),retrospectively. The 3-year and 5-year survival for those adenocarcinoma without distant metastasis undergoing pancreaticoduodenectomy were 50% and 32%. No long survival was found after the palliative operation. Conclusions Adenocarcinoma is the most common pathological type of PDMTs.No specific symptoms were shown in the early stage of PDMTs, US, CT and ERCP are the main diagnostic procedures. Radical pancraticoduodenectomy can prolong survival time and should be attempted for those without systemic dissemination.Palliative operations should be considered for tumors in advanced stage.