The present invention relates to a crystal of a benzofuran derivative free base and a preparation method. Specifically, the present invention relates to crystal A, crystal B, crystal C, and crystal D of N-((4,6-dimethyl-2-carbonyl-1,2-dihydropyridin-3-yl)methyl)-5-ethyl-6-(ethyl(tetrahyd ro-2H-pyran)4-yl)amino)-2-(piperidin-1-ylmethyl)benzofuran-4-carboxamide and a preparation method for the crystals. The crystals of the compound of formula (I) of the present invention have great crystal stability and provides improved uses in clinical treatment.
