The title compound 2-(2-Bromophenyl)-5-ethyl-1,3-dioxan-5-yl-methanol was prepared by the aldol reaction of 2,2-di(hydroxymethyl)butanol with 2-bromobenzaldehyde in the presence of SO 2− 4 /Fe 2 O 3 in cyclohexane and N,N-dimethylbenzamide, and its structure was characterized by melting points, elemental analysis, IR spectra, 1 H NMR and single-crystal X-ray diffraction. The crystal of the compound 2(C 13 H 17 BrO 3 · H 2 O belongs to orthorhombic system, space group Pccn, with a = 14.0856(3), b = 24.879(3), c = 7.8800(9) Å, = 90 , = 90 , = 90 , V = 2761.4(5) Å 3 , Z = 4, D c = 1.492 g/cm 3 , (Mo-K = 2.977 mm −1 , F 000 = 1272, the final R = 0.0381 and wR I > 2 I = 0 1015. X-ray diffraction results show that the 1,3-dioxane ring in the title compound is non-planar and exhibits a chair conformation. In addition, the fungicidal test showed that the title compound had good antifungal activity.