Quantitative dual energy computed tomography (DECT) allows to obtain both density and atomic number andthus can provide information about material composition.In this paper, a DECT reconstruction method for high energy X-rays (1∼1OMV) is proposed based on a basis material decomposition model. Our method is to be adapted for cargo inspection. The difTerence from conventional DECT methods is derived from considering pair-production effect in reconstruction. This is unnecessary for DECT In usual energy level (lower than IMV). Therefore, an approximation of the attenuation process is made: attenuation of photoelectric effect is ignored our reconstruction due to its tiny contribution to total attenuation of multi-MY Xray beams. Under this assumption, we set up our mathematical models based on the framework of the basis material method for DECT. Numerical experiments are performed to validate the effectiveness of our method. Results shows that our assumption and method are reasonable and feasible to be applied to real data. Discussion of the results and possible improvements for future work are presented in the end.