Abstract: At present, there is limited study on the relationship between Duncan-Chang constitutive model parameters and the saturation of collapsing loess. This paper uses the consolidated drained triaxial shear test on Jinnan collapsing loess. It studies the law of saturation for the Duncan-Chang model parameters. The results show that when the confining pressure increases, the stress-strain curves change from the weak hardening into strength hardening, and the volume changes also increase. The model parameters of C、、K、G、F、D、Rf can decrease as the saturation increases. But the model parameter n can increase as the saturation increases. The curve fitting is good.