Abstract: The refractory high-entropy alloy (RHEA) usually forms a multi-principal element alloy with atomic ratio or near equal atomic ratio via adding a variety of high melting point elements. It is expected to be used as a new type of anti-irradiation structural material in the new generation of advanced nuclear reactor system due to the excellent mechanical properties at high temperatures, corrosion resistance and radiation resistance. In the present study, the effect of cold rolling and heat treatment on Charpy impact properties of TiVTaNb RHEA with high strength-ductility trade-off was systematically studied by using the instrumented Charpy impact testing machine. The experimental results show that after cold rolling and heat treatment, the segregation of elements in the as-cast alloy disappears, and the alloy microstructure is equiaxed grains with uniform composition. No element segregation or second phase precipitation is observed inside the grains and at the grain boundaries of the homogenized alloy under SEM. Cold rolling and heat treatment can significantly improve the impact absorbed energy of the alloy. The impact absorbed energy of homogenized TiVTaNb alloy is 11.92 J, which is 2.3 times that of as-cast TiVTaNb alloy (5.15 J). The fracture mode of as-cast TiVTaNb alloy under impact load is a ductile-brittle mixed fracture mode dominated by ductile fracture. However, the fracture mode of homogenized TiVTaNb alloy is ductile fracture, with obvious fiber regions in the lower part of the V-shaped notch, larger bending degree and area of shear lips, deeper and larger dimples with small dimples distributed in it for both the crack initiation region and the crack propagation region, which all effectively dissipate more impact energy. The crack initiation energy and propagation energy of homogenized TiVTaNb alloy are both higher than those of the as-cast TiVTaNb alloy, especially the increase of crack propagation energy is larger, which is 2.88 times that of as-cast TiVTaNb alloy. This indicates that the cold-rolled and heat-treated TiVTaNb alloy has higher resistance to crack initiation and crack propagation, and its crack propagation rate is slower. The cold rolling and heat treatment processes do not change the impact deformation mechanism of the alloy. The deformation mechanism is synergized by dislocation activities and deformation twinning for both as-cast and homogenized alloys. However, the dislocation density and the number of deformation twins increase significantly during the impact deformation process of homogenized TiVTaNb alloy, which is the main contribution for the improved impact properties and the stronger crack resistance under impact loading.