Ocean and maritime security is the main concern and focus of the Obama administration’s Asia-Pacific rebalancing strategy.In order to meet challenges of anti-access and area denial capability from China，Iran and other states，and other non-traditional security threats，the United States has been strengthening“Indo-Pacific”maritime security cooperation.By enhancing the“Indo-Pacific”naval forces deployment，strengthening“Indo-Pacific maritime partnership”by high-level visits，military training and assistance，arms sales and technology transfer，vessel visits and port call，joint military exercises，and participating the regional maritime cooperation regime，the United States upgrades the level of maritime security cooperation with allies and partners.Japan，India，Australia and the Philippines and other allies and partners actively adjust their polices and see it as an opportunities to expand their national interests.The U.S.maritime security strategy adjustment has complex impacts on regional security environments.