The invention relates to a calcium titanium aluminate-mullite composite refractory and a preparation method thereof. The technical scheme adopted by the invention is that the preparation method comprises the following steps: selecting 40 to 45 weight percent of mullite particles, 10 to 20 weight percent of fine mullite powder, 20 to 30 weight percent of calcium titanium aluminate particles, 5 to 10 weight percent of silicon carbide fine powder and 5 to 10 weight percent of corundum fine powder as raw materials, adding 3 to 4 weight percent of pure calcium aluminate cement, 0.05 to 0.2 weight percent of water reducing agent and 4 to 6 weight percent of water, stirring for 6 to 8 minutes and then vibrating and forming; maintaining for 40 to 48 hours under the condition of room temperature and then drying for 20 to 30 hours under the condition of 90 to 115 DEG C to obtain the calcium titanium aluminate-mullite composite refractory. The preparation method disclosed by the invention has the characteristics of low cost, simple technology and high rate of finished product. The prepared calcium titanium aluminate-mullite composite refractory prepared by the method has the characteristics of relatively-low apparent porosity, relatively-high flexural compressive strength, small heat conductivity coefficient and excellent thermal shock resistance stability.