In order to utilize the strong alkaline waste mud in commercial concrete mixing plants, the artificial stone was prepared from strong alkaline waste mud of commercial concrete mixing plants simulated in laboratory. The influences and mechanism of metakaolin content and water-cement ratio on the strength of artificial stone were studied in detail. The phase composition and microstructure of artificial stone were analyzed by XRD and SEM. The results show that the addition of metakaolin significantly increases the compressive strength of artificial stone. The compressive strength increases most when the content of metakaolin is 6% (mass fraction), and the strength growth rates at 14 d and 28 d are 18.2% and 20.3%, respectively. The compressive strength of artificial stone increases first and then decreases with the increase of the water-cement ratio. The compressive strength at 14 d and 28 d reaches the maximum when the water-cement ratio is 0.44 and 0.46, reaching 44 MPa and 46 MPa, respectively.