Abstract: OBJECTIVE To investigate the incidence and pathogenic bacterial distribution characteristics of surgical site infection (SSI) after spinal surgery， analyze the risk factors of SSI after spinal surgery， and evaluate the direct economic burden caused by SSI. METHODS The Nosocomial Infection Surveillance was used for SSI surveillance. Data on 9 915 patients who underwent spinal surgery at the First Medical Center of the Chinese PLA General Hospital from 2019 to 2024 was retrospectively collected. A 1∶2 matched control group was established for patients with SSI. Conditional logistic regression was used to analyze the risk factors of SSI after spinal surgery， and marginal analysis was used to estimate the direct economic loss caused by SSI. RESULTS A total of 43 cases of SSI occurred after spinal surgery， with an incidence rate of 0.43%. The most common pathogenic bacteria were Staphylococcus aureus and Staphylococcus epidermidis. Surgical duration， incision length， NNIS score， intraoperative blood loss， cerebrospinal fluid leakage and postoperative drainage time were identified as risk factors for SSI (P＜ 0.05). Patients with cerebrospinal fluid leakage had a 9.280-fold higher risk of developing SSI than those without cerebrospinal fluid leakage OR=9.280, 95%CI: 1.047-82.256， P=0.045. The economic burden analysis showed that the median of total hospitalization costs for patients in the SSI group was approximately 86 000 yuan higher than that in the control group， and the median of total hospital stays was 31 days longer than that in the control group. When the total number of bed days were the same， with the marginal profit rate (M%) of 5%， 10% and 15%， the economic losses caused by SSI in the hospital amounted to 341 800 yuan， 683 600 yuan and 1 025 400 yuan， respectively. CONCLUSIONS Reducing cerebrospinal fluid leakage after spinal surgery can effectively decrease the incidence rate of SSI. SSI after spinal surgery imposes a significant economic burden on both patients and hospitals. More attention should be paid to the cost-benefit analysis of SSI， and relevant measures should be taken to reduce the incidence rate of SSI.