Based on the stress-strain relation of structural loess
the structural parameter with the shear strain
water content and consolidation pressure is explored and described by a mathematical formula. The formula can give the curve between the structural parameter and axial strain with a peak-value in which the coefficients are also determined by the experiment results. Further the structural parameter is applied to analyze stress-strain behaviors; and a structural stress-strain relation is set up. The rationality of structural parameter and its stress-strain relation is verified by comparing the calculating curves by the formulas with the testing curves.