The invention provides a photoinduced-nonlinear-expansion coordination polymer and preparation method thereof. The coordination polymer has a chemical formula of [Zn(iba)(tkpvb)Cl]n1, wherein iba represents p-iodobenzoate, tkpvb represents 1,2,4,5-tetrakis((E)-2-(4-pyridyl)vinyl)benzene, and n=3000-60000; and crystallographic parameters of: (1) crystal system: monoclinic system; (2) space group: Cc; (3) a = 28.6156(16) Å, b = 7.2901(4) Å, c = 21.5157(13) Å, β = 127.430(4)°, and V = 3574.2(4) Å3; (4) Z = 4; and (5) F(000) = 1680, R1 = 0.1363, wR2 = 0.3788, and GOF = 1.620; wherein iba represents p-iodobenzoate, tkpvb represents 1,2,4,5-tetrakis((E)-2-(4-pyridyl)vinyl)benzene, and n1=3000-60000. The preparation method of the coordination polymer of the present invention is simple, and has mild reaction conditions, and fast light conversion rate. Moreover, the coordination polymer undergoes an addition reaction, exhibits the photoinduced nonlinear expansion performance of the material, and affords a corresponding isomeric compound under the irradiation of light of various wavelengths.