Abstract: In order to improve the hot working ability of refractory high entropy alloys, the mixture gas of H₂ and Ar was introduced into the melting atmosphere by plasma assisted gas alloying, so that hydrogen was dissolved into Ti Zr Hf NbMo refractory high entropy alloys. The microstructures and properties of TiZrHfNbMo refractory high-entropy alloy under different H contents were studied. The results show that H does not change the composition of the alloy phase, but the compressive strength, hardness and elongation at room temperature decrease, and the elongation decreases from 21% to 19%.H addition significantly refines the dendrite spacing and reduces the number and size of secondary dendrite arms. The high temperature flow stress of the alloy after hydrogenating decreases from 622 to 498 MPa.