The invention discloses a method for fast preparing polycrystalline tetra calcium aluminoferrite. The method includes the steps that firstly, raw materials including calcium nitrate terahydrate, aluminum nitrate nonahydrate, iron nitrate nonahydrate and urea are weighed according to the mass ratio of 1:0.7942:0.8554:2.0413-2.1923; secondly, a proper amount of deionized water is added, and dispersion liquid with the concentration ranging from 0.5 mol / L to 0.8 mol / L is prepared and continuously stirred for 1.5 hours to 2 hours till the raw materials are completely dissolved; thirdly, the dispersion liquid is moved into a high temperature stove and heated to 500 DEG C to 510 DEG C in air atmosphere, after the constant temperature is kept for two hours, the dispersion liquid is taken out and grinded into particles with the particle size smaller than or equal to 0.15 mm, and the particles serve as a precursor ready for use; fourthly, the precursor is pressed into a thin piece with the diameter of 35 mm and the thickness smaller than or equal to 5 mm under the pressure of 25 MPa to 30 MPa; finally, the pressed precursor thin piece is heated to 650 DEG C to 950 DEG C at the heating rate of 10 DEG C / min, after the constant temperature is kept for 7 hours, the pressed precursor thin piece is taken out, fast cooled in the air and grinded, and the polycrystalline tetra calcium aluminoferrite with the hydration activity is obtained. The method is small in working procedure number, short in period and high in efficiency, the sintering temperature is 300 DEG C to 600 DEG C lower than the sintering temperature of a traditional method, and the method has the advantages of being fast, efficient and capable of saving energy, and is suitable for industrial large-scale application.