The invention discloses a method for purifying pseudomonas aeruginosa (PA) recombinant subunit genetic engineering protein vaccine Vac 14. The Vac 14 protein is obtained in the mode that active functional fragments of pseudomonas aeruginosa antigen molecules are recombined and confused, and escherichia coli genetically engineered bacterium expression is conducted. Technologies including high pressure bacterium breaking, GST affinity chromatography, PP enzyme restriction enzyme digestion, SPHP chromatography, G25 chromatography, Q HP chromatography and the like are adopted for genetic engineering bacteria, and the high-purity pseudomonas aeruginosa (PA) recombinant subunit genetic engineering protein vaccine Vac 14 is obtained. The method is simple and fast in purifying process, easy to amplify and good in repeatability, the obtained target protein is high in purity, and it is proved by animal tests that a mechanism can be effectively stimulated to generate high humoral immune response and a good immune protective effect.