Abstract: In order to study dynamic elastic modulus，damping ratio and its affecting facfors of subgrade filler of group B coarse grained soil for high speed railway， the consolidated undrained triaxial tests were carried out by large-scale trialxial test system． The results indicated that among many factors affecting dynamic modules and damping ratio， dynamic strain was the most important one． Dynamic modules decreased by exponent sign function and damping ratio increased by S-curve with the increasd of dynamic strain． Both dynamic modulus and damping ratio increased with the increase of confining pressure and loading frequency． Dynamic elastic modulus decreased with the increase of number of vibration，and the attenuation of dynamic elastic modulus increased when the dynamic stress level was high． According to the testing results，a model of both dynamic elastic modulus and damping ratio was established as a function of dynamic strain in consideration of confining pressure and frequency，which might provided reference for the dynamic parameters of coarse grained soil filler of subgrade of high speed railway