The invention discloses a preparation method of nano-modified recycled aggregate high-fluidity concrete, and belongs to the technical field of building materials. The method comprises the following steps: firstly, carrying out vibration screening, high-pressure water cleaning and low-temperature
drying pretreatment on recycled coarse aggregate obtained by crushing waste concrete; then preparing a composite modified liquid containing
nano silicon dioxide and nano
calcium oxide, and ensuring that the nano material is uniform and stable by adopting an
ultrasonic dispersion technology; soaking the pretreated aggregate in the modification liquid, promoting the nanometer material to deeply permeate in combination with pulse ultrasonic assistance and low-speed stirring, and performing gradient
drying to obtain modified aggregate; finally, mixing the
cement, the modified aggregate, the fine aggregate, the water, the water
reducing agent, the nano reinforcing agent and the modified
fiber according to an optimal proportion, stirring and forming step by step, and curing by a composite curing process. According to the invention, nano-composite modification and process collaborative optimization are utilized, so that the water
absorption rate of the recycled aggregate is remarkably reduced, and the
interface bonding force is enhanced.