For a period of time，the great powers have put forward their strategic adjustment by paying close attention to traditional competition and expanding to emerging fields. Because of national strength’s relative decline，the U.S. is shrinking its global strategy and obviously paying more attention to the Asia-Pacific region. Taking advantage of this opportunity，regional powers adjusted their military strategy. The great powers accelerate their military applications of high-tech；strengthen their control of global commons. Security cooperation is facing various new challenges. There are signs that the great powers games are stepping into new run-in period，international relations are fermenting a new round of realignment and regrouping. This change not only brings pressure on China’s security maintaining，but also provides new opportunities. To some extent，change is opportunity. China’s strategic thinking must adapt to the megatrends of international situation，innovate at the base of respecting historical law，inspire more strategic wisdom，and provide strong support and powerful guarantee to the great rejuvenation of the Chinese nation.