Objective To investigate the epidemiological data of postoperative venous thromboembolism (VTE) in elderly surgical patients in Peking Union Medical College Hospital in order to explore the risk factors for the disease. Methods Clinical data of 4 819 patients who underwent surgery in Peking Union Medical College Hospital from May 2016 to July 2016 were collected and retrospectively analyzed. Their baseline information, and VTE prophylaxis and incidence of symptomatic VTE after the operation and in 3 months after discharge were recorded. According to their age, the patients were divided into the elderly group (≥65 years old, n=925) and the young and middle-age group (<65 years old, n=3 894). The differences in the occurrence and prevention of VTE were compared between the 2 groups, and the risk factors related to the occurrence of VTE were analyzed. SPSS statistics 26.0 was used for statistical analysis. Student′s t test, U test, Chi-square test or Fisher exact test was employed for intergroup comparison depending on different date types. Results The incidence of postoperative VTE was 2.59% (24/925) in the elderly group and 0.33% (13/3 894) in the young and middle-age group, with the incidence in the elderly group about 8 times higher than that in the young and middle-age group (RR=7.952,95%CI:4.033-15.678, P<0.001). The incidence in the department of neurosurgery was the highest (16.67%, 4/24), significantly higher that in other departments (P=0.003). The proportion of 19 risk factors in the elderly group was obviously higher than that in the young and middle-age group, and the most-accounted top 3 risk factors were major surgery (>45 min), malignancy, and obesity (body mass index>25 kg/m²). Multivariate logistic regression analysis showed that swollen legs, current smoking, and duration of surgery >2 h were independent risk factors for postoperative VTE in elderly patients (P<0.05). The proportions of receiving mechanical prophylaxis and pharmacologic prophylaxis for high-risk patients were statistically higher in the elderly group than the young and middle-age group [51.42% (399/776) vs 39.21% (567/1 446), P<0.01; 31.44% (244/776) vs 20.95% (303/1 446), P<0.01]. Among the elderly patients with VTE, 70.83% (17/24) did not receive pharmacologic prophylaxis before onset, and 58.33% (14/24) only received mechanical prophylaxis, but still had symptomatic VTE. Conclusion The incidence of postoperative VTE is high in elderly patients than the young and middle-age ones. Physicians should strengthen perioperative pharmacologic prophylaxis for VTE to the elderly patients with swollen legs, current smoking or duration of surgery >2 h.