High-precision space cold atom clocks play an important role in basic physics researches, navigation and positioning systems, and deep space exploration in the future. Herein, a novel microwave cavity is presented, which combines laser cooling and in situ atom detection. In microgravity, 87Rb atoms can be captured and cooled at the center of the microwave cavity, and the cold atom sample can be interrogated by the microwave field of the cavity. The analysis shows that this scheme has considerable advantages over the existing space cold atom clock schemes in reducing the loss of cold atoms, the proportion of dead time, and the range of distributed phase shift in the cavity. The detailed structure and optical design of the microwave cavity are presented herein, and the microwave magnetic field inside the microwave cavity is simulated. The characteristic test is performed in the cavity, and it shows that the design of the microwave cavity meets the requirement of the uncertainty of the space cold atom clock being better than 1×10 -16.