Abstract: The energy spectrum response is important characteristic for X-ray ICT detector. But there exist many difficulties to measure these parameters by experiments. The energy spectrum response of CdWO₄ detector was simulated by using the EGSnrc code. Meanwhile the effect of detection efficiency was analyzed by the distribution of accelerator bremsstrahlung spectra and the X-ray spectrum hardening, and some theoretic parameters were offered for the consistent and no-linearity correction of detector arrays. It was applied to ICT image correction, and a satisfying result was obtained.