The invention belongs to the technical field of building ceramic production, and in particular relates to a method for producing phase-separated kiln-transformed decorative composite materials by using red mud through a roller kiln. Use red mud, feldspar, vanadium-titanium slag, quartz, borax, lepidolite and talc as raw materials, put it in a frit furnace, melt it at 1400-1500°C, water quench, crush and sieve, and take the sieved residue The materials are mixed together, which is the raw material for phase-separation kiln transformation; feldspar, clay, coke gemstone, pyrophyllite and avenzu stone are used as raw materials, put them in a ball mill, after 36 hours of ball milling, spray granulation, and put the granules in the mold , through pressing and forming to obtain a green body; the prepared phase-separation kiln transformation raw material is spread on the green body, and then dried and fired in a roller kiln to produce a phase-separation kiln transformation decorative composite material. The phase-splitting kiln-changing decorative composite material produced by the invention can meet all the performance and decoration properties of traditional ceramics, and does not use glaze pigments in the production process, which is a green and environment-friendly production process.