Introduction: simulation can mimic real clinical situation and physiologic response of a patient. So it helps students to practice in a controlled environment and improved learning experience. The purpose of this study was to examine extent of using simulation in nursing education and its effect on students’ knowledge, skills, confidence, anxiety and critical thinking. Methodology: A post-test control group, quazi-experimental design was used to study 58 second-year students selected conveniently from nursing faculty. The control and intervention group received the same theoretical materials and lab training. The intervention group additionally trained on high-fidelity simulation. A questionnaire was developed by researcher to measure variables of study. Nursing skills were measured by standard checklists. Results: the t test showed a statistically significant difference (p < 0.05) between the experimental and the control group in knowledge, critical thinking, and skills related to the part of clinical training included in the simulation sessions. In addition, the results indicated a statistically significant difference (p < 0.05) in level of anxiety, self confidence and communication between the experimental group and the control group. Discussion: the results of the current study is consistent with the results of many previous studies. Most studies showed that simulation has a positive effect on improving knowledge, skills and competency. Further studies are required with all year levels of nursing program. In addition, educator's competencies and other nursing skills are recommended to be included in the future studies.