The invention discloses a bi-component cement based composite material for 3D (three dimensional) printing as well as a preparation method and application thereof. The bi-component cement based composite material for 3D printing comprises a component A and a component B, wherein the component A is prepared from 34 to 40 percent of sulphate aluminium cement, 0 to 6 percent of inorganic powder, 40 to 44 percent of tailing machine-made sand, 2.5 to 3 percent of high-molecular polymer and the balance of a retarder, a water reducer, a size stabilizer, a defoaming agent and water, the pumping performance can be well kept for a long time, an industrialized process of pre-stirring production in a mixing plant, transportation, and using in a construction site can be realized; the B component is prepared from a coagulate promoting agent, a thixotropic agent, a defoaming agent and water, the component is stable in form and can be stored for a long time or produced in a concentrated manner. After A and B are respectively pumped in a 3D printer, through high-speed stirring and being mixed by an extrusion head, the composite printing material can be extruded out, the time of coagulation is short, the strength is high, the adhesion is good, the stability is strong, the constructive continuity and building strength requirements of building 3D printing can be met, the industrial production and promotion of the cement based 3D printing material are facilitated, and the application of a 3D printing technology in buildings can be effectively promoted.