Abstract： Affected by the US-Soviet bipolar system, US-India maritime cooperation is not well developed during the Cold War. Since the 21st century, US-India maritime cooperation has gradually entered a deep-water zone, and realized a series of achievements. Democratic identity, maintenance of the Indian Ocean sea route security, and balancing China, are factors to boost the US-India maritime cooperation. At present, the US-India strategic elites have reached a basic consensus on promoting maritime cooperation, and Japan, Australia as well as other US allies are actively “matchmaking”. Therefore, the US-India cooperation will develop further, which will affect the regional security. On the one hand, it will intensify the naval arms race in the Indo-Pacific region, making marine hot issues continue to ferment; on the other hand, it will increase Chinas insecurity, causing Sino-US relations to be more complex, and it will impose negative impacts on Sino-India relations.