To investigate the frequency of deep vein thrombosis (DVT) in patients aged over 80 years on admission after intertrochanteric femur fracture and to explore the risk factors of DVT. Descriptive study. Place and Duration of the Study: Department of Orthopaedics, China-Japan Friendship Hospital, Beijing, China, from 1st January 2019 to 31st December 2022. A group of patients aged over 80 years with intertrochanteric fracture were included according to the presence or absence of DVT confirmed by ultrasonography on admission. The patients were divided into the non-DVT and DVT groups. Clinical data were retrospectively compared between the two groups and analysed by multivariate logistic regression to screen risk factors of DVT. A total of 130 patients meeting the inclusion criteria were enrolled, and 37 of them had DVT on admission, with a prevalence of 28.5%, including 25 (67.6%) distal peripheral DVT, 11 (29.7%) proximal central DVT, and 1 (2.7%) mixed DVT. The American Society of Anaesthesiologists (ASA) classification, Charlson comorbidity index, the serum levels of D-dimer, fibrinogen degradation products, albumin, potassium, inorganic phosphorus, and calcium showed significant differences between the two groups (p <0.1). Multivariate analysis identified increased D-dimer (>6.005 mg/L), decreased albumin (<36.45 g/L), and reduced potassium (<3.650 mmol/L) as independent factors for DVT in aged intertrochanteric fracture patients (AIFPs). A high incidence of DVT was revealed in AIFPs, and elevated D-dimer levels, reduced albumin levels, and reduced potassium concentrations were shown to be correlated to DVT. Intertrochanteric fracture, Deep vein thrombosis, Aged patients, Risk factor, Multivariate logistic regression.