Objective: Recently, practical training of skills in medical education centers based on educational curriculums has become significantly important. The objective of the present study was to investigate the level of learning to work with defibrillator by interns of the emergency ward with two methods of educational simulator and lecture. Method: In this cross-sectional analytical study, all interns working in the emergency unit of Mohammad Rasool Allah hospital during the 6 months of the study in 2015 entered the study. The subjects were randomly assigned into two groups consisting of 76 participants (training to use defibrillator by educational simulator and lecture). The level of training for each person was determined by a questionnaire designed by the researcher in the periods of pre-test, post-test after a month. In addition, the practical skills were investigated using a synthetic model. Results: There was no significant difference between the pre-test scores in two groups (P = 0.199). The scores for post-test were higher in simulator training group compared to the group trained in the classroom (P <0.001). In order to assess the interns more efficiently, the practical skills of them were studied, in which, the simulator-trained group showed a higher score compared to the group trained in the classroom. (P <0.001). About a month later, the scores from the interns' evaluation showed that the simulator-trained group had a clearly higher score, compared to the group trained in the classroom (P <0.001). Conclusion: Based on the results of this study, training with the simulator led to a more effective theoretical and practical learning of interns. It is recommended that the primary training of using defibrillators be considered as a part of the internship program.