Duncan-Chang nonlinear model has been widely used in numerical analysis of stress-strain in engineering. There exists insufficiency when Duncan-Chang model applied to complex stress conditions; this model is based on the axisymmetric stress conditions. We compared the model predictions with the experimental results of intact clay by true triaxial tests. The results demonstrate the applicability of Duncan-Chang model under complex stress condition. According to the analysis of the relationship between intermediate principal stress and the maximum principal strain under true triaxial stress conditions

and the maximum principal strain includes not only the maximum principal strain but also the strain

is caused by differences between the intermediate principal stress and the maximum principal stress. Based on Duncan-Chang E-B model

we proposed a method for determining Duncan-Chang E-B model parameter under different intermediate principal stress ratios and also established the modified Duncan-Chang model E-B model under complex stresses. The modified Duncan-Chang E-B model is reliable by comparison of the true triaxial test results of Xi'an intact clay; it is shown a way to use Duncan-Chang E-B model in complex stresses path.