This work focuses on the reactivation of fluid catalytic cracking (FCC) catalyst via mixed acid to leach out pollutant Ni and Fe oxides and reserve acidic sites provider Al2O3 in zeolite. The micro-structure, morphology and chemical composition of reactivated catalysts were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), and energy dispersive X-ray analysis (EDXA), respectively. The change of micro-structure and catalytic performance of the catalyst after reactivation were discussed. The blocked micro- and meso-pores in the spent catalyst are opened by acid leaching, and the specific surface area is doubled, which is close to that of fresh catalyst. The catalytic performance of the reactivated catalyst is evaluated in heavy oil micro-reactor. It results in 6.3% increase of conversion than the spent catalyst, and 2.31% increase of gasoline yield and 11.60% increase of diesel yield. This method for spent FCC catalyst reactivation has strong practicability and is of great significance for environment protection and resources recycling.