The invention discloses a preparation method of an all-
solid-waste
building material, which comprises the following steps: S1, raw materials of the all-
solid-waste
building material comprise steel
slag,
lithium slag,
carbide slag and water according to a
mass ratio of (11-13): (4-6): 1: (2-4); s2, uniformly mixing and stirring the raw materials in the S1,
casting and molding, curing for 2-3 days in an environment with the temperature of 15-25 DEG C and the
humidity of 45-55%, and demolding; and S3, after demolding, carrying out
carbonization maintenance in an environment with the temperature of 15-25 DEG C and the
humidity of 45-55% to obtain the all-
solid waste
building material. According to the all-solid-waste building material and the preparation method thereof, the steel slag, the
lithium slag and the
carbide slag are adopted as raw materials, the building material with the strength reaching up to 30 Mpa is prepared, it is guaranteed that the
compressive strength is not smaller than 24.3 Mpa, meanwhile, it is guaranteed that the
drying shrinkage rate is smaller than 0.29%, the
sulfate erosion resistance
expansion rate is smaller than 0.07%, and the all-solid-waste building material can replace baking-free bricks to be used in buildings.