Objective To investigate the risk factors of thrombotic microangiopathy (TMA) complicated by multiple injuries.Methods 387 patients with multiple injuries admitted to our hospital from September 2018 to September 2024 were retrospectively selected and divided into TMA group (46 cases) and non-TMA group (341 cases) according to whether they had TMA. Multivariate Logistic regression analysis was conducted to analyze the risk factors of TMA in patients with multiple injuries and construct a prediction model. Receiver operating characteristic (ROC) curve verified the performance of the prediction model.Results Age, body mass index, ISS score, lactate dehydrogenase, VWF, complement C3a, complement C4d, coma ratio, shock ratio, blood transfusion ratio and infection ratio in TMA group were higher than those in non-TAM group (P<0.05), and hemoglobin, platelet count and ADAMTS13 were lower than those in non-TAM group (P<0.05). High ISS score, older age, coma, blood transfusion, infection and increased level of complement C3a were risk factors for TMA in patients with multiple injuries (P<0.05), and increased level of ADAMTS13 was protective factor (P<0.05). The area under the curve of the prediction model for TMA in patients with multiple injuries was 0.867 (95%CI:0.830-0.900, P<0.001), and the Hosmer-Lemeshow test P>0.05. Conclusion Higher trauma degree, older age, coma, blood transfusion, infection, increased level of complement C3a and decreased ADAMTS13 are related factors for TMA in patients with multiple injuries. The prediction model based on the above risk factors has high efficiency