Objective To evaluate the reliability and validity of trauma team activation criteria (TTAC) in emergency triage. Methods Triage nurses and research nurses picked a convenient sample of 100 trauma patients on their first arrival at the emergency department,independently assessed each patient with TTAC and compared the 2 results of each patient, to identify interrater reliability of TTAC. A total of 4054 patients who visited the emergency department for the first time due to trauma from July to December 2020, were selected and assessed with TTAC, and 2 other measures (one was the ISS score, and the other was intervention and patient outcomes, with ISS score ＞15 or the use of emergency intervention measures and poor patient outcomes being defined as severe trauma respectively).The undertriage rate, and overtriage rate,sensitivity, specificity, and area under the ROC curve, of TTAC, against the 2 other measures, were calculated and analyzed. Results The assessment results of the 100 patients by triage nurses and research nurses reached a concordance rate of 0.79, and a Kappa value of 0.625（P＜0.05）.Taking the ISS score＞15 points as the gold standard for severe trauma, the undertriage rate, overtriage rate, sensitivity, specificity, and area under the ROC curve, of TTAC, were 4.63%, 47.45%, 95.37%, 90.33%, and 0.953, respectively.Taking the use of emergency intervention measures and poor patient outcomes as the gold standard for severe trauma, the undertriage rate, overtriage rate, sensitivity, specificity, and area under the ROC curve, of TTAC, were 4.22%, 41.84%, 95.80%, 95.70%, and 0.958, respectively. Conclusion TTAC enjoys good reliability. In terms of validity, it has a high diagnostic efficiency and a low undertriage rate, versus a high overtriage rate. Nurses are able to identify patients with severe trauma with the use of TTAC, which still needs further revision, so as to reduce the overtriage rate.