This application relates to the technical field of building materials, and discloses a machine-made sand conditioner for concrete, including: polycarboxylic acid mother liquor, diethanol monoisopropanolamine, triisopropanolamine, glycerin and sodium sulfate; the solvent is water . The machine-made sand conditioner of the embodiment of the present disclosure has abundant hydroxyl groups, is weakly alkaline, does not contain chloride ions, is non-toxic and non-corrosive, and is a high-performance green environmental protection material. The composition is simple, and the excellent performance can be achieved by adjusting the reasonable ratio of the components. As an admixture for concrete, machine-made sand can be used as the sand material in concrete. No waste liquid is generated, no cleaning is required after stirring, no production wastewater is generated, and no waste gas is generated. The application also discloses a concrete and a preparation method thereof.