The invention provides high-performance decrosslinked rubber 
asphalt and a preparation method thereof, when the rubber 
powder is deeply decrosslinked, a 
polyolefin modifier and an SBS modifier (
styrene-butadiene block 
polymer) are doped as separants of decrosslinked rubber, so that the 
viscosity of the decrosslinked rubber can be reduced, the cohesion of the decrosslinked rubber is prevented, the 
polyolefin modifier is rapidly melted at high temperature, the rubber particles are rapidly opened, and thus the 
dispersity of the rubber particles can be remarkably enhanced. Meanwhile, the 
polyolefin and the SBS modifier can obviously improve the performance of the 
asphalt. The decrosslinked rubber is deeply degraded, so that the cohesive force of the rubber 
asphalt is improved, the Brookfield 
viscosity of the rubber asphalt is reduced, the construction performance is improved, and a relatively high rubber mixing amount is achieved.