The invention provides a method for separating molybdenum, copper and rhenium in low-grade molybdenum concentrate through pressurized oxidization. The method includes the following steps that firstly, the low-grade molybdenum concentrate is screened after being ground, and then water is added so that ore pulp can be prepared; secondly, the ore pulp, nitrogen-containing compound and sulfuric acid are added into a pressure kettle to be subjected to a pressurized oxidization reaction, and a sizing agent is obtained; thirdly, vacuum filtering is performed, and filter cakes and first filter liquor are obtained; and fourthly, the filter cakes are washed, and industrial molybdenum oxide is obtained; and the washing liquid obtained after washing is combined with the first filter liquor, then iron powder, scrap iron or iron wires are added into mixed liquid, standing and filtering are performed after uniform stirring, filter residues and second filter liquor are obtained, the filter residues are smelted to make copper, molybdenum and rhenium in the second filter liquor are adsorbed through ion exchange resin, and then molybdenum and rhenium are desorbed and recycled in steps. By means of the method, the one-time molybdenum recycling rate can reach 90%, the molybdenum oxidation rate is high, the required pressure is low, the reaction time is short, and the comprehensive recycling effect of metal is good. In a word, the method is reasonable in process design, good in using effect and high in economic value.