The calibration of an imaging spectrometer by using the diffuser method should consider not only the accuracy of calibration instruments, but also the effects of instrument and geometric parameters from the imaging spectrometer on calibration results. According to the calibration principle of imaging spectrometer using the diffuser method, this paper deduces the expression of the collected signal electron number in each spectral channel of the imaging spectrometer by taking the parameters as self-variables, and it analyzes the effects of the incident angle of standard lamp, the distance of standard lamp to the diffuser, the slit direction and the observation incident angle of the imaging spectrometer on the electron number collected by the detector pixels. The results show that when the F number is set to be 3 and 4, the entrance pupil in 0.1-0.2 m, the standard lamp illuminating angle less than 12° and the distance of the standard lamp in 0.5-2 m, the change of the signal electron number can be less than 1%.It satisfies the accuracy need of the calibration by using the diffuser method.