Background: The most critical issue in providing appropriate services to the large number of patients referring to emergency wards is the proper conduct of triage, by considering the shortage of personnel and the insufficiency of facilities. The learning of the triage can only be possible through retraining of nurses. Therefore, this study attempts to compare the two educational methods, competency-based training and lecture, and to compare their impact on the knowledge and performance of nurses regarding triage. Materials and Methods: In this semi-experimental study, 75 nurses employed in the emergency wards of Fatemeh Al-Zahra, Rasul Akram, and Shahid Motahari hospitals were selected based on the inclusion criteria of the study. Nurses were placed in three groups (one control and two intervention, n=25) through a simple random method person groups of control and intervention. The researcher-made tools included "triage knowledge test" with 15 questions, and "triage performance checklist" that included 50 scores. The validity of the tests was performed through the formal and content method with the opinion of experts, and the reliability was verified through the test-retest method for which the Pearson Correlation Coefficient was 0.88. After examining the level of knowledge and performance, the intervention was carried out through two methods in the two groups. Eventually, a renewed test and the performance checklist were carried out for all the three groups and data were analyzed using SPSS software V. 21. Results: There is a significant difference between the mean score for knowledge and performance in the two groups before and after intervention (P<0.05). Also, there was a significant difference between the two intervention groups and control in the mean difference of scores for knowledge and performance in conducting the triage (P<0.05). Comparison between the two intervention groups demonstrates that in the performance part, the competency-based group had a higher performance score (P<0.05). Conclusion: Education and training through the competency-based method have more effect than lecture training on the performance of nurses in the field of triage. It is suggested to use this method for retraining of nurses in the field of triage.