Abstract: Soft-X-ray spectrometers are used in diagnosis of the equivalent radiation temperature of hohlraum in indirectly driven inertial confinement fusion experiments. Uncertainties of the soft-X-ray optical elements and electronic devices of the spectrometer, and the recovery methods are determined, which influence the measurement of the radiation temperature. The uncertainty analysis method based on Monte-Carlo sampling is implemented and uncertainty of the radiation temperature including all kinds of uncertainty factors is obtained. The alignment of signals from different detection channels of the multi-channel spectrometer is analyzed separately, which proves to be a large uncertainty source.