The invention provides a microwave blackbody emissivity measurement device, which comprises a turntable base, a transmitter, a receiver and a closed-loop control system. The device further comprises arotating platform, a transmitter support, a blackbody lifting mechanism, a receiver support, a reference calibration body and an emissivity measurement module, wherein the rotating platform is arranged on the turntable base; the side surface of the rotating platform is connected with the bottom of the transmitter support; the blackbody lifting mechanism is arranged on the platform surface at thecentral position; the rotating platform drives the transmitter support and the blackbody lifting mechanism to simultaneously and coaxially rotate; the blackbody lifting mechanism is used for adjustingthe height of the reference calibration body and the microwave blackbody so as to enable the centers of the reference calibration body and the microwave blackbody to be coplanar with a rotating axisof the receiver support; the receiver support drives a receiving antenna of the receiver to perform rotary scanning in the pitch direction under the control of the closed-loop control system so as toobtain scattering data; and the emissivity measurement module calculates the emissivity of the microwave blackbody according to the scanned scattering data.