Background: Cardiopulmonary arrest is one of the leading causes of death outside the hospital. It threatens the lives of the mother and fetus, so cardiopulmonary resuscitation can save the woman and the fetus's life. Training a maternity nurse through simulation regarding cardiopulmonary resuscitation during pregnancy is most important for properly taking care of such emergency situations during pregnancy and saving women and fetal lives. The purpose of the present study was to assess the effect of a simulation intervention on maternity nurses' performance regarding cardiopulmonary resuscitation. Method: A quasi-experimental research design (one group pretest, posttest) was adopted. The interviewing questionnaire and maternity nurses' performance observational checklist were used throughout the study. The study was conducted at the Obstetric and Gynaecological Departments affiliated with Benha University Hospital, Health Insurance in Benha, and Quesina General Hospital. Results: There were highly statistically significant improvements regarding knowledge and practice after simulation intervention and during follow-up compared to pre-intervention (P=0.000). Conclusion: Simulation intervention improves knowledge and practice of maternity nurses regarding CPR. Recommendations: the current study showed that simulation intervention programs should be systematically applied, and continuous evaluation of nursing performance should be conducted to help improve nursing performance quality. It is also recommended that hospital managers carry out systematic planning to improve the knowledge and performance of nurses regarding CPR.