The invention relates to a high-performance molybdenum-rhenium alloy bar. The high-performance molybdenum-rhenium alloy bar is composed of following components of, by mass, 5-50% of rhenium and the balance molybdenum. The invention further relates to a preparation method for the high-performance molybdenum-rhenium alloy bar. The method sequentially comprises the following steps that firstly, a molybdenum source and a rhenium source are weighed correspondingly according to the component ratio of the molybdenum-rhenium alloy bar, pretreatment is conducted, and molybdenum-rhenium alloy powder isobtained; secondly, the molybdenum-rhenium alloy powder is put into a designed die cavity for pressing forming treatment, and a pressed blank is obtained; thirdly, the pressed blank is subjected to high-temperature sintering treatment under a reducing atmosphere or inert gas or vacuum condition, and a sintered blank is obtained; fourthly, the sintered blank is subjected to rolling deformation treatment, and a rolled bar blank is obtained; and fifthly, the rolled bar blank is subjected to annealing heat treatment, and the high-performance molybdenum-rhenium alloy bar is obtained. A molybdenum-rhenium alloy material prepared through the preparation method is fine and uniform in crystal grain and high in compactness and strength.