Japanese auto industry has rapidly developed after the war,and it has become the world's big and strong country of car production.Japanese three auto companies as the research object,by using the information of the year 2006-2010 co-applicants from joint patent applications in the J-GLOBAL database,combined three major R&D cooperation network.And then apply the theory and method of social network analysis to calculate and analyze different indexes.Research shows that:research and development cooperation net...