Abstract: How to make a strategic response to the institutional complexity in transnational M&A integration process determines whether the strategic intention of transnational M&A can be achieved. Based on the perspective of adaptation and innovation, we identify two types of strategic responses to institutional complexity in the process of M&A integration: institutional adaptation and institutional co-creation, empirically test the impact of prior M&A motives on the selection of strategic response during the post-merger integration process, as well as the moderating effect of M&A experience and organizational slack on these relationships. The study finds that exploitative M&A firms tend to choose to implement institutional co-creation strategy, and the exploratory M&A firms tend to choose to implement institutional adaptation strategy, while the M&A experience and organizational slack positively adjust the above relationships.