Abstract: In recent years, mergers and acquisitions related to military technology production and R&D in the United States have become more and more frequent. What is the impact of mergers and acquisitions on military technology innovation? Combining the knowledge-based view with the characteristics of national defense industry, this paper proposes the possible influence mechanism of mergers and acquisitions activities of national defense enterprises on their military technological innovation. Through the empirical study of eleven large defense enterprises in the United States, it is found that technology mergers and acquisitions have a positive effect on the performance of military technological innovation of defense enterprises, but the degree of influence decreases gradually; non-technology mergers and acquisitions have no significant impact on the performance of military technological innovation in the short term, but have a negative impact in the long term; the absolute knowledge scale and relative knowledge scale of the target party has non-linear and negative impact on the performance of military technological innovation, respectively.