The foundation soil of the buildings and structures is often in complex initial stress states. The dynamic torsional shear triaxial tests are carried out on undisturbed and remodeling loess under different complex initial stress states by using the remolded DTC-199 torsional cyclic load triaxial apparatus, and the effects of each complex initial stress state parameter on dynamic shear modulus of loess are discussed. Results show that, other conditions being the same, the influence of angles of initial principal stressα0on dynamic shear modulusGdof loess show a trend of the biggerα0is, the smallerGdis. The effect laws of efficient of initial intermediate principal stressb0onGdof loess are not obvious. When the dynamic shear strain is larger, the bigger initial deviator stress ratioη0is, the smallerGdof loess is. The influence of initial average principal stresspm0on loess is significant. The biggerpm0is, the biggerGdof loess is.Gdof undisturbed loess is greater than that of remodeling loess under the complex initial stress states.