The invention relates to a doxycycline soluble powder and a preparation method thereof. The method uses a solid dispersing technology, and comprises heating a solid dispersion carrier to 80-100 DEG C into a molten state, adding a methanol solution of the doxycycline, stirring, mixing uniformly, steaming to remove the methanol, cooling, crushing, and sieving to obtain the finish product. According to the invention, a solubility of the doxycycline is improved, the preparation technology is simple and the cost is low.