Abstract: There exist many difficulties and deficiencies only depending on collimators to depress the scattering photon in industrial X-ray computerized tomography(ICT). In order to solve these questions it is necessary to correct for scattered photons. Based on a ideal model the theoretical formula on scattered photon calculation for industrial X-ray computerized tomography was deduced. The scattered photon numbers were calculated by present formula, and were compared with that from experiments. It is seen that both the calculated and the experimental scattered photon numbers are in agreement. Meanwhile the feasible plan is put forward for the software correction of scattered photons in ICT.