The invention relates to a preparation method of mesoporous beta-TCP (tricalcium phosphate) powder. The preparation method comprises steps as follows: 1), two parts of transparent solutions containing surfactants, cosurfactants and water are prepared; 2), a calcium-containing inorganic salt solution and a phosphorus-containing inorganic salt solution are added to the transparent solutions respectively and stirred, a phosphorus-containing inorganic salt mixed solution is added to a calcium-containing inorganic salt mixed solution, the pH value is adjusted, and the mixture is stirred to obtain an emulsion; and 3), the mixture is left to stand, subjected to ageing, centrifugation, washing and drying, placed in a high-temperature furnace, heated and subjected to heat preservation, and mesoporous beta-TCP powder is obtained. The preparation method has the benefits as follows: 1, the operation is simple, energy consumption is low, the cost is low, the reaction condition is mild, and harmful substances are not generated in the preparation process; and 2, the obtained mesoporous beta-TCP powder has smaller pore diameter and has a three-dimensional pore structure, the average pore diameter of the mesoporous beta-TCP powder is 8.80-21.36 nm, and the specific surface area is 10.11-153.43 m<2> / g.