The invention discloses a preparation method for a high-entropy alloy. A pure element or master alloy powder mixture is adopted as a raw material and is directly put into discharge plasma sintering (SPS) equipment, a vacuum hot pressing reaction is conducted, and the bulk high-entropy alloy is fast sintered and synthesized; and the integration of the densification of the alloy bulk material and the solid solution phase of the high-entropy alloy is achieved through the precise control over the SPS sintering parameters, and the dense high-entropy alloy bulk material is obtained at a time. The high-entropy alloy prepared through the technology is high in densification, uniform in structure and excellent in mechanical performance. The preparation method has the outstanding beneficial effects that the equipment and process are simple, the efficient and fast functions are achieved, the production cost is low, and the reliability is high and is suitable for the industrial production of the high-entropy alloy.