The invention discloses a high-performance reinforced mortar suitable for thick-layer spraying and a preparation method thereof. The high-performance reinforced mortar is mainly prepared from ordinary portland cement, silica fume, coal ash, an expanding agent, a water reducing agent, cellulose ether, anti-crack fibers, and graded sand in a certain mass percent, wherein the mass percent of each composition is as follows: the cement 24%-32%, the silica fume 4%-8%, the coal ash 4%-8%, the expanding agent 2.0%-3.5%, the water reducing agent 0.1%-0.15%, the cellulose ether 0.05%-0.2%, the anti-crack fibers 0.05%-0.1%, and the graded sand 56%-66%. The high-performance reinforced mortar of the invention has strength of M60-M80, and can be used to meet reinforcing requirements of high strength concrete of strength grade C60. The high-performance reinforced mortar has good pumping performance, and is suitable for mechanized spraying construction. Moreover, the high-performance reinforced mortar has excellent substituted performance and a single spraying construction thickness of 40mm, and can be used to meet construction requirements of large-size members and thick-layer reinforcement.