Despite the passage 10 years since Peter Senge's theory of "learning organization", there are many ambiguous in the theory which to need be ecarified through doing further research. In this paper, the nature of organizational learning mechanisms along with the model of learning organization is discussed and also organizational learning mechanisms in the national company of oil refinement and distribution of oil products of Iran-Tehran is discussed through a field research .Time domain of assessment of OLMs has been considered for about one year. With valuing of the questionnaire , the result of the Binomial test indicate that the mentioned company has utilized appropriate organizational learning mechanisms including the learning environment, identifying learning and development needs, meeting learning and development needs and applying learning in the workplace.