The invention provides ecoquinate soluble powder and a preparation method thereof. The preparation method comprises the steps: evenly mixing ecoquinate and a solid dispersion carrier together; heating the mixture to a fusing state at the temperature of 120DEG C to 150 DEG C; then, airing and crashing the mixture at room temperature; adding anhydrous dextrose to obtain the ecoquinate soluble powder. The decoquinate soluble powder comprises 1 percent to 20 percent of ecoquinate, 4 percent to 80 percent of solid dispersion carrier and anhydrous dextrose. The prepared soluble powder has good solubility and high stability, the property and the solubility of the soluble powder are not changed after being stored for 6 mouths under an accelerating test condition (40DEG C+/-2DEG C) or being stored for 1 year at room temperature (25DEG C+/-2DEG C ), the content of the ecoquinate soluble powder is reduced and meets the requirements of galenic pharmacy, the effective period of the ecoquinate soluble powder can be as long as 3 years by calculation, the content reduction is not obvious under an illumination experiment condition, and the content of drug active ingredients can be maintained above 90 percent for four hours in water. A prepared drug preparation has good effect and convenient use and has good popularization and application value.