The invention discloses an eight-channel radiometer capable of realizing a self-calibrating function. The radiometer also has a radiation observation and self-calibrating function. The eight-channel radiometer comprises an observation light path, a related photon generating module, a scanning motor module, a multiplexing telescope module, a collimating light path module, a light splitting and gathering light path module, a photoelectric detection and signal processing module. The decay factors of the optoelectronic circuit of the eight-channel radiometer can be evaluated by disposing the related photon calibrating device in the radiometer, and then the periodic correction of the calibration coefficient of the eight-channel radiometer can be realized. The related photon calibrating device is absolute, and the tracing to the high-precision measurement standard is not required, and therefore the higher calibrating precision can be achieved.