As the construction of a new-type of major-country relation between China and the U.S. is deepened in recent years，security relation has become a new highlight in the bilateral relations along with economic and trade relation and cultural exchange. In particular，the construction of a new-type of military relation between the two countries has made steady progress，high-ranking military officials of both countries have made frequent mutual visits，joint military exercises and trainings have been carried out many times，mechanism consultations have made ample achievements，major progress has been made in the construction of China-U.S. “trust measures and mechanism”，and their cooperation in areas of non-traditional security governance（e.g. coping with climate change，preventing maritime disaster，preventing the spread of weapons of mass destruction，cracking down on terrorism，and fighting against Ebola）has propelled other countries to participate in global governance. In the meantime，China and the U.S. are faced with a range of new challenges. The two countries have conspicuous and frequent conflicts on issues such as the Diaoyu Islands，cyber security and construction of islands and reefs in the South China Sea. Those issues have become key barriers to developing the China-U.S. strategic mutual trust and security relation. But the breakthroughs made by the two countries in cyber security cooperation provide a valuable reference to solving those issues.