Through the study of single microwave quantum detection of single carrier signal and thermal noise signal, the response ability of single microwave quantum detector based on microwave optical upconversion to weak microwave signals is verified. Based on the quantum optical theory, the second-order coherence properties of microwave signals are studied experimentally. It is proved that the second-order quantum coherence of single carrier signal and thermal noise in microwave band has the same quantum properties as the coherent light source and thermal light source in optical band.