Abstract:   Abstract: By taking Japan’s fast developing period from 60’s to 80’s of last century as the background, the cooperation in innovation activities is focused by analyzing the patenting information of the database of triadic patent families built by OECD. Five Japanese firms and two American benchmark firms are taken as the sample firms. Patents of all over the world of two five-year periods and two single years are also investigated. The results show that Japanese firms have higher cooperation level during their catching-up period, which exhibits an exogenous characteristic. The project-level cooperation trend for patenting in Japanese firms is also higher than that at the world level, which shows that the team work cooperation culture of Japanese firms offers more information sharing in the innovation. The inspiration that China and Chinese firms could draw from is that industrial policies leading to technological cooperation in technical advance should be attached much importance and corporate culture that is beneficial to cooperation should be cultivated.

Key words: cooperation, innovation, patent, heterogeneity, complementarity