The invention relates to a chemically-reinforced cover plate glass, and a preparation method thereof. According to the preparation method, under heating conditions, a glass composition is subjected tomelting homogenizing, moulding, and annealing so as to obtain cover plate glass; the cover plate glass is dipped into a molten salt containing potassium ions for ion exchange so as to obtain the chemically-reinforced cover plate glass. The surface compressive stress of the chemically-reinforced cover plate glass ranges from 770 to 860MPa, and the compressive stress layer thickness ranges from 36to 50m; the chemically-reinforced cover plate glass is subjected to boiling in a 1mol/L NaOH solution for 10h, glass surface weight loss ratio is equal to or lower than 3.56wt%. According to the preparation method, the specific composition and the weight range of the glass composition are limited, chemical reinforcing technology is adopted, so that the obtained chemically-reinforced cover plate glass is relatively high in surface stress and stress layer thickness, the surface scratch-proofness of glass substrate obtained via chemical tempering is improved, dropping resistance and wear resistance are improved, and the alkali resistance is excellent.