The diagnostic value of neutrophil-to-lymphocyte ratio (NLR), monocyte-to-lymphocyte ratio (MLR), and platelet-to-lymphocyte ratio (PLR) in predicting fracture-related infection (FRI) in tibia fracture patients remains to be explored. A retrospective controlled study was carried out with 170 tibia FRI patients and 162 control subjects. The following information was evaluated at admission: age, gender, clinical features, number of white blood cells (WBCs), neutrophils, lymphocytes, monocytes, red blood cells (RBCs), platelets, level of hemoglobin, C-reactive protein (CRP), and erythrocyte sedimentation rate (ESR), as well as NLR, MLR, and PLR. The number of lymphocytes, RBCs, and platelets in the FRI group was higher than those in the control group, while the number of neutrophils and ESR level was lower (P < 0.05). The level of NLR and MLR was significantly lower in patients with tibia FRI than in control subjects (P < 0.05). Both indicators were positively correlated with WBCs, CRP level, and ESR level (P < 0.001). The results of logistic regression analysis showed that five variables including NLR, MLR, platelets, fracture pattern (closed or open fracture), and site pattern (single or multiple site) were used to construct the FRI risk predictor. The ROC curve analysis result showed that FRI risk predictor yielded the highest AUC, with a sensitivity of 91.2% and a specificity of 90.1%, and made the distinction efficiently between tibia FRI patients and non-FRI patients. NLR and MLR were decreased in tibia FRI patients compared to non-FRI patients. Both indicators had a positive correlation with WBCs, CRP level, and ESR level. FRI risk predictor constructed based on five variables including NLR and MLR had a high diagnostic value for tibia FRI.