A novel benzenesulfonate-imidazole complex of nickel Ni(Im)6(C6H5SO3)2 was synthesized by solvothermal method with nickel sulfate, sodium benzenesulfonate and imidazole as main raw materials. The structure, composition and thermal stability of complex were characterized by single X-ray crystal diffraction, inductively coupled plasma optical emission spectrometer, infrared spectroscopy, powder X-ray diffraction and thermogravimetric analysis. The molecular structure was determined. The specific surface area and the pore structure were determined by N2 adsorption-desorption test. The result shows that the complex belongs to monoclinic system, P21/c space group, exhibiting a 3D spatial structure. It exhibits high phase purity and thermal stability. The cell parameters of complex are a=8.377 3(4) , b=10.151 8(5) , c=20.526 3(10) , α=90°, β=90.292 0(10)°, γ=90°, V=1 745.63(15) 3, Z=2, Mr=781.52, F(000)=812, μ=0.737 mm-1, Dc=1.487 g·cm-3, R1=0.042 1, wR2=0.110 3. Then, the Knoevenagel reaction was used as a probe to test the catalytic performance of complex. The experimental results show that under room temperature and solvent-free conditions, the complex could complete catalytic reactions in a relatively short time and exhibit high catalytic activity.