The study aimed at studying the green HR practices as a mediator in the relationship between organization learning and competitive advantage applied in Joint companies in petroleum sector. The data was collected from a random sample of 377 employees in the joint sector using a questionnaire that was designed and tested. Statistical techniques was used to test the research hypotheses and answer the research questions. The results of the study can be summarized as follows; There is a statistically significant relationship between organizational learning and green human resources practices; organizational learning and competitive advantage. Also, there is a statistically significant relationship between green human resources practices and competitive advantage. Additionally, there is a statistically significant relationship between green human resources practices as a mediating variable between organizational learning and competitive advantage. Thus, this study emphasizes on developing the knowledge, skills, and awareness of employees in petroleum sector companies regarding the concepts of organizational learning, green human resources practices and competitive advantage in terms of their importance, characteristics, strategic sources, types, obstacles, and the bases for each concept. Keywords organizational learning; green human resources practices; competitive advantage