In this paper, different kinds of organic amines are used to modify ZIF-8 catalysts prepared via solvothermal method, and effects of organic amine structural characteristics on the activity of ZIF-8 for Knoevenagel condensation were discussed. Results show that ZIF-8 modified by organic amine still maintains the rhombohedral dodecahedron structure and possesses regular morphology, without obvious difference from that of unmodified materials. The BET specific surface areas of ZIF-8 modified by 1,2-propylenediamine, diethylenetriamine and triethylenetetramine are 1893, 1885 and 1861 m2?g-1, respectively, decreased by about 6.5% compared with the unmodified materials, mainly being due to the blockage of pores for ZIF-8 by organic amines. When ethanol works as solvent, the amount of catalyst is 0.6 mol%, the reaction temperature is at 80oC and reaction time keeps for 210 min, 1, 2-propanediamine modified ZIF-8 exhibits the highest catalyst activity, yield of ethyl α-cyanocinnamate reaches 97.8%. After 10 cycles, yield of this reaction is still up to 90%, 35.3% higher than that of unmodified ZIF-8. Amines modified ZIF-8 can improve the amount of activity site, in which, N sites existed in 1, 2-propanediamine are easier to meet with the reactant due to the short chain and small steric hindrance, which combines with the original imidazole N site on ZIF-8 to coordinate with α-H on the methylene of benzaldehyde through lone pair electrons, so as to improve the catalytic activity of the catalyst clearly.