Space military strategies provide the guidelines and foundations for the development of space forces. By sorting and analyzing the contents of U.S. space military strategy in recent years， the trends of the strategies are summarized. The militarization of space is obviously recognized. The U.S. space military strategies show a trend of developing the theory of space active confrontation， transforming into an independent space combat domain， promoting the application of campaigns and tactics， and strengthening the combination with business alliances. Furthermore， the space strategies show significant influences on the development of the U.S. space force， which manifests in improving the actual combat capabilities and accelerating the systematic transformation of space force.The impacts of the U.S. space strategies on the space posture and space activities are concluded， which probably provides references for China’s space force construction and the struggle for space supremacy.