The invention relates to a high-temperature-resistance VNbMoTa high-entropy alloy and a preparation method thereof, and belongs to the field of metal materials and preparation thereof. An atomic percent expression of components of the alloy is VaNbbMocTad, wherein a is not more than 35 and not less than 10, b is not more than 45 and not less than 20, c is not more than 25 and not less than 5, andd is not more than 45 and not less than 20. Needed raw materials are pure metal of vanadium, niobium, molybdenum and tantalum. After scales are removed, the raw materials are put in a vacuum arc furnace for smelting; and after 4-6 times of smelting, a solid-solution alloy of a single-phase BCC mechanism can be obtained. The prepared VNbMoTa high-entropy alloy achieves excellent room-temperature plasticity and high-temperature strength, can be on active service at high temperature of 1200 DEG C, and can be widely applied as a high-temperature bearing piece in the fields of aerospace, automobileand oil exploration.