Objective:To investigate the risk factors of multi-drug resistant organism（MDRO）infection in orthopedic trauma patients.Methods:A retrospective case series study was made on clinical data of 95 orthopedic patients with in-hospital wound infection admitted to West China Hospital of Sichuan University from January 2020 to December 2020，including 71 males and 24 females at age of 14-70 years［（42.6 ± 13.8）years］. MDRO infection occurred in 38 patients（DRO group），while not in 57 patients（non-MDRO group）. Etiological characteristics of wound infections were observed. Univariate analysis was used to compare variables between the two groups，including baseline data（gender，age，length of hospital stay，chronic comorbidity）and injury as well as hospitalization information（transfer from another hospital，emergency admission，time from injury to first treatment，open injury，combination with fracture，wound contamination，depth of wound，ICU stay，number of operations，cumulative operation time，type of incision，length of hospital stay before diagnosis of infection，type of antibiotics used，usage of hormones/immunosuppressive agents，level of hemoglobin/serum albumin/blood glucose on admission）. Binary Logistic regression was used to analyze independent risk factors for MDRO infection.Results:A total of 119 pathogenic bacteria were detected on the wound，including 21 gram-positive cocci（18%），91 gram-negative bacilli（76%）and 7 others（6%）. Top five strains were Acinetobacter baumannii，Enterobacter cloacae，Escherichia coli，Staphylococcus aureus and Pseudomonas aeruginosa. Univariate analysis showed the two groups had significant differences in terms of length of hospital stay，wound contamination，ICU stay，length of hospital stay before diagnosis of infection，type of antibiotics used and levels of hemoglobin and serum albumin on admission（ P < 0.05），but not in gender，age，hypertension，diabetes，transfer from another hospital and emergency admission（ P > 0.05）. Multivariate Logistic regression analysis showed MDRD infection was obviously correlated with the long hospital stay（ OR = 1.033， 95%CI 1.005-1.061， P < 0.05），time from injury to first treatment over 6 hours（ OR = 4.282， 95%CI 1.174-15.616， P < 0.05），types of antibiotics used ≥ 3（ OR = 7.486， 95%CI 2.451-22.863， P < 0.05）and low level of hemoglobin on admission（ OR = 0.973， 95%CI 0.962-0.985， P < 0.05）. Conclusions:For orthopedic trauma patients，MDRO infection is independently associated with long hospital stay，time from injury to first treatment，type of antibiotics use and level of hemoglobin on admission，suggesting that decreased length of hospitalization，shortened time of first wound treatment，individualized and rational usage of antibiotics and timely correction of anemia are important measures to prevent MDRO infection.