The invention belongs to the field of radiotherapy sensibilization medicines, and relates to albumin nanoparticles capable of double-stage oxygen carrying and a preparation method and application thereof. The albumin nanoparticles are mainly prepared from albumin, perfluoro-carbon and catalase, the particle size of the albumin nanoparticles is even, the property is stable, the biosecurity is good,and the problem of radiotherapy resisting of solid tumors can be solved. Experimental results show that the nanoparticles can target the tumors and improve tumor hypoxia by means of double-stage oxygen carrying, for specific performance of double-stage oxygen carrying of the nanoparticles, the high-oxygen-carrying perfluoro-carbon directly supplies oxygen (first stage oxygen carrying) to the hypoxic tumors directly through oxygen concentration gradient difference, meanwhile, the catalase conducts catalytic hydrolysis on high-concentration hydrogen peroxide on the tumor portions to generate oxygen for indirect oxygen carrying (second stage oxygen carrying), through synergism of first stage oxygen carrying and second stage oxygen carrying, a tumor hypoxia microenvironment is reversed, and effective sensibilization is conducted on oxygen-dependent tumor radiotherapy.