Abstract: The technology spillover of alternative development in homogeneous enterprises and the partnership of enterprise innovation were studied， and the classic AJ model in the field of enterprise R&D cooperation was expanded. Based on the different relationships of competition and cooperation， the expected profit models in terms of noncost sharing， cost sharing and information sharing were constructed respectively， and the solution was given by using backward induction. By comparing R&D investment and production of Nash equilibrium in various states， the conclusion was drawn that R&D expenditure decreased and production grew with the increase of technology spillover rate. The results showed that the spillover effect generated by R&D behaviors in the alternative development of homogenous industries exerts a positive impact on the cooperation among enterprises.

Key words: homogereous enterprise, alternative development, Nash equilibrium, spillover