The invention discloses high-thixotropy 3D (three-dimensional) printing concrete and a preparation method thereof. One cubic meter of concrete comprises, in weight percent, 35-40% of cement, 0.1-0.4%of polycarboxylate water reducers, 0.1-0.4% of polypropylene fibers, 1.0-3.0% of special thixotropic agents of the 3D printing concrete, 12.5-14.5%% of water and the rest sand. The 3D printing concrete is prepared from the special thixotropic agents of the 3D printing concrete, high in thixotropy, good in rheological property, high in foam stabilizing ability and good in pumpability, extrudabilityand buildability, cannot crack in the printing process and has early-strength performance, the 3D printing setting time is shortened, and the concrete is not obviously deformed after multilayer loadscover. Raw materials of the printing concrete are easily acquired, low in cost and simple in production process, and printability, outer surface flatness and early strength of the 3D printing concrete can be greatly improved.