Context: as one of leader organizations in knowledge management, Iran Khodro Industrial Group has been tried hard efforts to find appropriate solutions to develop knowledge process and correct management for its employees. By distance from traditional economic based on knowledge, knowledge altered to basic asset of organizations and its management seems to be essential affair. In modern economic knowledge is main source of economical and industrial improvement. In the research, it has been studied the effect of transformational leadership as one of modern leadership procedures in the organization as well as knowledge management as one of key drivers of organisational performance on the improvement of organizational innovation.Objective: This study aimed to Investigating the mediating role of knowledge management in the relationship between transformational leadership and organizational innovation.Methods: The method of the research is descriptive and its type is correlation in method and its aim is applicative. The Population of this study consisted of all staff Iran Khodro Industrial Group Shirvan That sample was selected by utilizing simple random sampling and 52 individuals selected. data were collected through transformational leadership questionnaire (Bass & Avolio, 2000), knowledge management (chen & et al, 2011), organizational innovation (The combination of questionnaires Jimenez et al, 2008 Pennyadz, 2006, Prajogo & Sohal, 2006), that their validity and reliability were confirmed.Findings: Pearson correlation analysis showed that a positive relationship was found between transformational leadership and organizational innovation. The relationship between transformational leadership and knowledge management, was positive. The results of path analysis suggest that transformational leadership directly (b=0.71), and indirectly with the mediating role of knowledge management (b=0.20) is on effective organizational innovation (Total: b=0.91). The knowledge management also hasa significant impact on organizational innovation (b=0.28).Conclusion: results showed that knowledge management is the main condition to organizational innovation. In addition, organizational managers can work better in promoting organizational knowledge management through benchmarking transformational leadership style.