The dynamic shear modulusG of soil was determined using a dynamic triaxial test system (DTTS) together with a iftting method. First, a novel linear relationship betweenG and damping ratioλ was proposed, which was used to select the appropriate G. Then, a hyperbolic model was constructed using the optimized parametersa andb representing the intercept and slope, respectively, from the linear regression of 1/G and dynamic shear strainγd. Finally, the differences between the tested and predicted results forG were analyzed for different soil types. The experimental results show that this linear relationship can overcome the shortcomings of the nonlinear relationship found in the large deformation stage and can predictλ in the hysteresis loop that is not closed case. In addition to Baoji loess,G was slightly larger (10%) than the experimental curve in the elasto-plastic stage; however, the experimental results show that the attenuation curve ofG for Baoji loess is greater than the calculated value in the elasto-plastic stage. The test and analysis results will improve the knowledge of the dynamic properties of soils and also provide reliable values ofG for further evaluation of seismic safety at engineering sites.