Introduction: Diabetes is the most common metabolic disease and a major global challenge that is the leading cause of death in the industrialized and developing world. Therefore, this study was performed on some influential factors on severity of diabetic foot ulcers and predisposing of limb amputation. Materials and Methods: In this cross-sectional descriptive-analytic study, 4436 cases of diabetic patients admitted to Khatam-ol-Anbia hospital of Shoushtar from 2010 to 2016 were studied. The data in this study included three sections: demographic information, ulcer severity based on Wagner’s criterion, and clinical and laboratory data. Then data were analyzed using descriptive and analytical statistical tests. Results: This study included 4436 patients with diabetes with a mean age of 54.36 ± 42.68 years. 421 patients (9.4 percent) had a history of diabetic foot ulcers. Also, 385 patients (8.6%) had a history of limb amputation. In this study, 596 patients (13.4%) had a history of smoking and the relationship between smoking and drug use with the severity of ulcer was significant (p = 0.006). In this study, in the majority of patients with diabetic foot ulcers (60.3%) had severity of ulcer based on Wagner’s criterion was second grade. In terms of bacteriology, 57.7% of the patients during the admission period had cultures of the ulcer site discharge, that the most commonly of mass in 26.7% of cases was Staphylococcus aureus. In this study, the relationship between type of bacteria and severity of ulcer and limb amputation was significant (P <0.05), This means that the ulcers that had negative coagulase-staphylococcus bacteria, were higher the severe ulcer and amputations. Conclusion: In this study, the relationship between type of bacteria and severity of ulcer and limb amputation was significant, this means that the ulcers that had negative coagulase-staphylococcus bacteria, were higher the severe ulcer and amputations.