The invention discloses brine concrete, a preparation method and a construction method. The brine concrete is prepared from brine, light burning powder, medium sand and macadam, wherein the mass radio of the brine to the light burning powder to the medium sand to the macadam is (1.4 to 1.5) to 1.2 to (3.1 to 3.5) to (4.5 to 5.0). The preparation method of the brine concrete comprises the steps of S1 brine mixing and S2 mixed material mixing. The construction method of the brine concrete comprises the steps of S1 roadbed trimming; S2 filling; and S3 joint construction. The raw material of the brine concrete can be obtained by extracting large amount of waste old brine resources in a salt lake, the cost is low, the initial coagulation is quick, and the temperature in a condensation process is relatively high, so that a road can be open as early as possible. The road constructed by the brine concrete provided by the invention is high in strength, high in rigidity, has no corrosion problem and has low maintenance cost at the later stage. Furthermore, the preparation method of the brine concrete provided by the invention is simple and convenient, and the construction quality of the pavement can be effectively ensured by combining the construction method and the brine concrete.