Objective To analyze the direct economic burden caused by surgical site infection (SSI) in orthopedics and joint surgery, and provide evidence-based support for intervention measures. Methods 3 348 hospitalized patients in the department of orthopedics and joint surgery of a hospital from July 2021 to July 2023 were selected. They were divided into an infection group and a control group based on whether they had SSI. The propensity score matching (PSM) method was adopted to match the two groups of patients in a 1 ∶1 ratio. The length of hospital stay and various hospitalization expenses between patients with different types of SSI and control group were compared. Results Among 3 348 hospitalized patients, 259 had SSI, with an incidence of 7.74%. Superficial incisional wound infection had the highest number of patients (n=177, 68.34%), followed by deep incisional wound infection (n=65, 25.10%), organ/space infection had the lowest number of patients (n=17, 6.56%). After PSM matching, 257 pairs were successfully matched, with a matching rate of 99.23%. Infection group extended length of hospital stay by 18 days compared with the control group (P<0.001). The total hospitalization expenses and individual hospitalization expenses of infection group were all higher than those of the control group (all P<0.001). Among the various expenses, difference in drug expense was the largest, with an increase of 5 067.83 Yuan in Western medicine (P<0.001) and 957.30 Yuan in antimicrobial agents (P<0.001). Patients with different types of SSI all had longer hospital stay compared with the control group. Patients with deep incisional wound infection, superficial incisional wound infection, and organ/space infection had an extended hospital stay of 26,18, and 13 days, respectively (all P<0.05). The total hospitalization expenses, Western medicine expenses, and antimicrobial agent expenses of patients with different types of SSI were all higher than those of the control group (all P<0.05). Conclusion The occurrence of postoperative SSI in patients in the department of orthopedics and joint surgery can prolong the length of hospital stay, resulting in huge economic losses for the patient and the hospital. Effective control of healthcare-associated infection is of great significance for optimizing medical resources, improving medical quality, and ensuring patient safety.