The invention relates to the technical field of compound sugar, in particular to an erythritol crystal, which comprises erythritol and sweet agents accounting for 1 to 2.5 percent of the weight of the erythritol. A preparation method of the erythritol crystal comprises the following steps that the erythritol and the sweet agents are mixed and dissolved to obtain liquid solution, the solution is simultaneously evaporated and crystallized, and the erythritol crystals are obtained; the erythritol and the sweet agents are mixed and are dissolved to obtain liquid solution, the liquid solution is subjected to non-evaporation crystallization, the filtering is carried out after the crystallization completion, and the erythritol crystals are obtained; the erythritol and the sweet agents are mixed in a solid from; and the mixed solids are subjected to melting, crystallization, crushing and drying to obtain the erythritol crystals. The sweetness of the erythritol is improved and reaches more than 80 percent of the sweetness of the cane sugar, the consistency of ingredients of compound products of the erythritol and the sweet agents is realized, the problem of cocrystallization of the erythritol and the sweet agents easily carbonized at high temperature is solved, the crystallization rate is improved to the maximum degree, the crystallization efficiency is 5 to 20 percent higher than that of the traditional crystallization technology, and the application field of the product is enlarged.