The invention discloses a preparation method of 
lithium hexafluorophate. The preparation method includes preparing gas mixture of 
phosphorus pentafluoride and 
hydrogen chloride; preparing 
anhydrous hydrogen fluoride mixed liquor containing 
lithium fluoride; realizing 
combination reaction of the gas mixture and the mixed liquor; realizing quick cooling 
crystallization of 
lithium hexafluorophate liquor; separating 
solid from liquid; realizing rotary 
vacuum drying; and finally obtaining lithium hexafluorophate 
crystal. The preparation method is a high-efficiency gas, 
solid and liquid three-phasereaction method, purity of the quality of products is guaranteed, simultaneously, yield further can be increased, the yield of the products can reach 90% at least, 
moisture and 
metal impurities in the products are effectively reduced, 
zero emission of the 
phosphorus element can be realized in aftertreatment, requirements of current national 
environmental protection policy are met, byproducts of 
hydrochloric acid and 
hydrofluoric acid can be sold to bring certain income, production cost is further lowered, the quality of the products is further improved by means of adopting high-specification equipment and materials, requirements of high-end 
electrolyte products can be met, and the preparation method has excellent practicality and can produce good economic benefit and social benefit.