A pair of Z-E enaminonitrile isomerisms 2-(3,4-dimethoxyphenyl)-3-((3-methoxyphenyl)ami- no)acrylonitrile (C₁₈H₁₈N₂O₃, M_r = 310.34) were synthesized and separated by flash column chromatography, and their structures were determined by IR, ¹H NMR, ¹³C NMR, MS and single-crystal X-ray diffraction. The crystal of compound 2a belongs to the monoclinic system, space group C2/c with a = 33.805(7), b = 5.4496(12), c = 18.401(4) Å, β = 112.45(2)º, V = 3133.1(12) Å³, Z = 8, μ = 0.091 mm^-1, D_c = 1.143 g×cm^-3, the final R = 0.0491 and wR = 0.1439 for 2764 observed reflections (I > 2σ(I)). The crystal of compound 2b belongs to the triclinic system, space group P1, with a = 8.8403(7), b = 9.0390(6), c = 12.0044(74) Å, α = 72.075(5), β = 86.291(5), γ = 81.216(5)º, V = 901.82(10) Å³, Z = 2, T = 293(2) K, μ = 0.079 mm^-1, D_c = 1.143 g×cm^-3, the final R = 0.0474 and wR = 0.1377 for 3176 observed reflections (I > 2σ(I)). The crystal packing of 2a and 2b is governed by intermolecular N(2)–H(2)···N(1) and N(2)–H(2)···O(2) interactions respectively to stabilize the structure.