目前双能量X射线图像系统都是通过使用高能和低能透射信号相结合的方法（计算出与有效原子序数相关的R值）来识别物质，但物体厚度对双能量透射图像的R值有很大影响，即会影响物质分类识别的准确性。为此提出了一种改进的用两种能量的透射信号比来消除物质厚度的影响，并以优化的透射信号估算的面积吸收系数来代替透射信号，用以识别物质的数值计算优化算法，通过实验数据分析和对该算法的评估证明，由于此算法可以大大减小厚度的影响，使误判率减小，从而提高了物质分类识别的准确性。

Dual-energy X-ray imaging system combining the high and low transmission signal to serve the method of object classification(calculate R related with effective atomic number) at present.But(object's) thickness has great effect on dual-energy transmission imaging.Videlicet,(object's) thickness influences the veracity of object classification.This paper put forward an improving numerical optimized method by the ratio of two transmission signal to eliminate the effect of the thickness,with optimized area absorption coefficient transmission signal to replace the transmission signal.This method can weaken the effect of(object's) thickness on R,decrease the probability of inaccuracy and improve the veracity of classification by analyzing and evaluating experimental data.