In order to obtain higher responsivity and spatial resolution under poor illumination condition, interline transfer CCD camera can be designed to work in time delay and integration (TDI) mode similar to TDI CCD. Whereas it is found that outputs of some pixels are obviously lower than others′ as interline transfer CCD camera works in TDI mode in laboratory radiometric calibration experiments. In result, photo response non-uniformity(PRNU) and signal noise ratio(SNR) of the system become worse. An improved radiometric calibration method of interline transfer CCD camera based on TDI working mode is put forward. In this method, TDI stage is taken into account in PRNU and SNR algorithms and system performance is improved remarkably with few influences on use. Results of validation experiments prove that the improved radiometric calibration method can efficiently improve SNR and lower PRNU of the system. In addition, characteristic of the system can be reflected better with the improved radiometric calibration method. As working in 32 TDI stages, PRUN is reduced from 4.88% to 0.86% and SNR is improved about 2.9%.