This paper aims to achieve two purposes. First, to discuss the US Asia-Pacific policy from the Obama Administration to the TrumpAdministration. The second is to compare the similarity and differences between Obama and Trump’s Asia-Pacific policy. This paper extracts several hypotheses from John J. Mearsheimer’s Offensive Realism. In this paper, I argue that China’s activities in the Asia-Pacific were the pivotal factor for the US to alter its Asia-Pacific policy. Since the more China promotes different actives in the region, the more active the US becomes in ensuring its leadership. Besides, after comparing these two strategies, I believe that both were similar. Even there were some discrepancies on the way to implement them, the goal of both strategies was the same.