Abstract: based on the resource dependency theory and the three helix theory, we investigate the impact of institutional proximity, geographical proximity and technological proximity on cooperative innovation and test the moderating role of technological diversification by using 2002-2016 years' patent data of electronic information industry. The result shows that: (1) both institutional proximity and geographical proximity have a significant positive impact on cooperative innovation performance, and there is a reverse U relationship between technological proximity and cooperative innovation performance. (2) Technology diversification as a moderator increases the positive relationship between institutional proximity and cooperative innovation performance, and it also strengthened the reverse U relationship between technological proximity and cooperative innovation performance. (3) Geographical proximity plays a significant role in promoting the cooperative innovation performance of government-enterprises and enterprises-enterprises. There is a reverse U relationship between technology proximity and cooperation innovation performance of the collaboration of enterprises- enterprises, however technology proximity has a significant negative impact on the cooperation innovation performance of collaboration of enterprises- universities and government-enterprises. Our research extends the scope of the three helix theory and provides theoretical support and decision-making basis for the cooperation innovation among government, enterprises and universities.