The basic objective of this study was to mediate the relationship between organizational intelligence, knowledge management and organizational effectiveness at Ports and Maritime Organization of Tehran Province. The population of the research were the staff in the PMO of Tehran.257 employees were selected through random sampling. A questionnaire consisting of 42 questions of knowledge management (Sales and Jones, 2002), with leadership and management, teamwork and learning communities, knowledge sharing, knowledge creation, digital justice, ideas and mission, strategy, culture, intellectual capital, organization learning dimensions (a=0.87) and to measure organizational intelligence, a questionnaire of 49 questions (Albrecht, 2002) and dimensions of strategic vision, shared fate, appetite for change, spirit, unity and agreement, application knowledge and performance pressure (a=0.90) was used and to assess organizational effectiveness a questionnaire with 28 questions (Parsons, 1979), and the dimensions of (adaptation or innovation), (organizational commitment or target acquisition), (job satisfaction or unity), (organizational health or maintain the pattern) (a=0.83) were used. Processing of the data using structural equation modeling showed that the mediation role of knowledge management in the relationship between organizational intelligence and organizational effectiveness is approved. This means that the emphasis on knowledge management and its compliance from organizations causes the effect of each of the variables of organizational intelligence and organizational effectiveness on the successful implementation of the other in the organization.