Background There were many literatures reporting the impact of frailty on postoperative complications, however, studies according to stepwise propensity score matching (PSM) to offset the influence of age were limited.Methods We gathered data for all patients undergoing short-level posterior lumbar interbody fusion from January to December 2021. Accroding to Fried frailty phenotype, we segragated patients into three groups (not-frailty, pre-frailty, and frailty), then, stepwise propensity score matching for age, sex, American Society of Anesthesiologists (ASA) and fusion levels were performed to keep comparable clinical data between groups. Uni- and multivariate logistic regression were used to identify the impact of clinical demographics on postoperative complications.Results A total consecutive 559 patients with complete medical records were enrolled (237 males and 322 females; mean age 72.55 ± 5.86 years). After PS matching, we found pre-frail patients were more vulnerable to develop urinary retention ( p = 0.031 ) and surgical site infection ( p = 0.021 ) than non-frail patients. Meanwhile, longer length of stay (LOS), ambulation time and removal of urinary catheter time were observed in pre-frail patients. However, there was significant difference only in LOS between pre-frail and frail patients. Binary logistic regression revealed that C-reaction protein (CRP) and frailty status were independently associated with postoperative complications between non-frail and pre-frail patients, while only CRP was independently correlated with that of between pre-frail and frail patients.Conclusions In this study, after PS matching, we found higher rate of urinary retention and surgical site infection in pre-frail patients than that of non-frail patients. CRP was independently related to postoperative complications, while frailty status was only independently associated with postoperative complications between pre-frail and non-frail patients. And pre-frail/frail patients tended to have severer stress response than that of non-frail patients.