Abstract: In biological system,bivalent ligands often possess increased functional affinity for their receptors compared with monovalent ligands.Based on the information of 3D structure of AHAS-imazaquin(IQ) complex,8 symmetrical bivalent molecules of imazapic were designed and synthesized.Their structures were confirmed by IR,1H NMR and elementary analysis.The preliminary bioassay results showed that the inhibition rate to the acetohydroxyacid synthase from dimeric compounds were less potent than that of imazapic.And the inhibition rate to the growth of rape (Brassica campestris L.) root from bivalent compounds were very close to that of imazapic at concentration of 100 μg/mL.