The atomic clock, as the most precise timing instrument at present, is playing an important role in various fields of national economy and security. By operating atomic clocks on earth orbit satellites, many high-precision time synchronization and comparisonrelated applications can be implemented on a large scale on the earth. Unlike previous space cold atomic clocks that achieve microwave and atoms interaction by launching cold atoms cloud to traveling two microwave cavities, this article proposes a new space cold atomic microwave clock scheme based on in situ detection in the cavity. This scheme completes the laser cooling of rubidium 87 atoms, atoms and microwave interaction, cold atom detection, and other clock processes in the same microwave resonant cavity. It is possible to more fully utilize the microgravity environment to increase the duty cycle of the interaction time between atoms and microwaves in the clock cycle. Therefore, the impact of the Dick effect on the performance of atomic clocks is reduced. This article introduces the design and working principle of this kind of cold atoms microwave clock system, provides performance analysis and expected frequency stability in a microgravity environment, and finally shows that in the ground test results of the clock prototype. The tested 1. 35×10 -12 τ -1/ 2 frequency stability of the cold atom microwave clock demonstrates the potential performance of the clock operating in microgravity environments.