The invention relates to a high-infrared reflectivity orthogonal yttrium manganate powder based on a molten salt method and a preparation method thereof. The invention adopts the technical scheme thatthe preparation method comprises the following steps: proportioning according to the mass ratio of manganese dioxide to yttrium oxide of 2:1 to obtain an ingredient I; burdening according to the massratio of sodium chloride to potassium chloride of 1:1 to obtain an ingredient II; then burdening according to the mass ratio of the ingredient I to the ingredient II of 1:(3-5) to obtain an ingredient; ball-milling the ingredient for 10-30 minutes, putting in a crucible, then putting the crucible in a muffle furnace, increasing the temperature to be 700-900 DEG C at a rate of 3-5 DEG C/min, performing heat preservation for 2-4 hours, performing furnace cooling and discharging to obtain a calcined product; respectively cleaning the calcined product for 3-5 times by using primary deionized water and secondary deionized water, performing suction filtration and drying to obtain the high-infrared reflectivity orthogonal yttrium manganate powder based on the molten salt method. The preparationmethod provided by the invention has the characteristics of short production period and low energy consumption, and the prepared high-infrared reflectivity orthogonal yttrium manganate powder based onthe molten salt is high in infrared reflectivity, high in purity and good in stability.