Background: Disaster nursing is a new specialty, the most common challenges faced by nurses in this regard are inadequate levels of preparedness, poor formal education, lack of research, ethical and legal issues and issues related to their role in disasters. The purpose of the study was to evaluate the effect of disaster management training intervention on competency of nurses working in primary health care centers. Design: A quasi-experimental design was used. Sampling and setting: All sixty nurses working in the two primary health care centers (named Quiply and Bahary) at Shebin El-kom district, Menoufia Governorates, Egypt was recruited after using a multistage sampling technique to select study settings. Instruments: Four instruments were used: as A structured interviewing questionnaire, Disaster Management Knowledge Questionnaire, Disaster Nursing Competencies Questionnaire and Nursing Skills Checklist Measurement, Results:  The total score of knowledge about internal disaster preparedness guidelines among nurses revealed a highly significant improvement (p<0.000) in all knowledge items including the five subgroups, as well as grand total knowledge score that was increased from a range of 1.7% - 6.7% pre intervention to 31.9%- 78.3 post intervention and the effect of disaster management training nursing intervention on total score levels of competency (subdomains as well as grand total score) about disaster management among studied nurses pre and post intervention revealed a highly significant improvement (p<0.000) in all competency items including the ten subdomains. The grand total competency score that was increased from a range of 1.7% - 25% pre intervention to 64.1%- 107.4% post intervention Conclusions: Application of disaster management training intervention is beneficial in improving knowledge and enhancing competencies among nurses working in primary health care centers.  Recommendations: Conducting continuous training intervention about disaster management that aims to raise levels of knowledge and competency of nurses and how to treat with any disaster situations is very urgent in PHC.