The invention discloses carbon/calcium aluminate composite powder and a preparation method thereof. The prepared calcium aluminate cement contains a proper amount of elemental carbon which is a mixture containing carbon in various structural forms, wherein the actual content of the carbon is 0.3 to 2 percent. The preparation process comprises the following steps: firstly, proportioning raw materials such as calcium peroxide, organic acid calcium, aluminum powder and aluminum oxide according to stoichiometric ratio, wherein the organic calcium is one of calcium oxalate, calcium gluconate, calcium citrate and calcium stearate; secondly, mixing the weighed raw materials, then forming the uniformly-mixed materials and preparing the carbon/calcium aluminate composite powder by using a self-propagating high-temperature synthesis method. The preparation method has the advantages of high product purity, high energy utilization rate, economy and environment friendliness; the preparation method is in line with the sustainable development concepts of energy conservation and consumption reduction as well as emission reduction and environmental protection.