The effect of grain refinement and trace yttrium addition on dynamic behavior of 93W-4.9Ni-2.1Fe alloy was investigated. The true stress-strain curves obtained from dynamic compression tests show that strain hardening and thermal softening effects are present in the alloy, and the maximum dynamic strength and elongation increase with increasing of strain rates. Compared with the conventional 93W-4.9Ni-2.1Fe alloy, the fine-grained 93W-4.9Ni-2.1Fe alloy exhibits relatively higher strength and elongation under the same compression condition. In particular, the occurrence of obvious adiabatic shear bands in fine-grained alloy under lower high-strain-rate (1900 s-1) indicates that the propensity to adiabatic shear localization are enhanced significantly by grain refinement. Additionally, trace yttrium addition can improve the dynamic strength and elongation of tungsten heavy alloy.