Abstract: On the basis of flight test mission analysis for X-37B vehicle, it is pointed out in this paper that X-37B is not an aerospace vehicle nor a global quick attack platform, but a flight demonstrator of space access capabilities with low cost; its role is in space rather than in the air. By flight tests and flight demonstrations, the aim is to turn X-37B into a reusable orbital transfer vehicle. From some historic events, such as US major adjustments of 2010 space strategy, the postponement of ISS operation and the out of commission for space shuttle, the background of X-37B development is analyzed, which is closely related with the development trend of US space missions. From the analysis, it is suggested that two major transfers of the US space strategy adjustments must be paid special attention to, especially their background. It is important to understand the role of ISS to foresee the future development of manned space missions. US adjustments of space strategy makes the manned space missions to return to near earth orbit. Based on China’s current capabilities, it is suggested that the manned space tasks of China should focus on near earth orbit, with different kinds of capabilities for earth orbit missions.