Objective:To study the influence of different amino group introductions on the antiplatelet aggregation activities of pyridazinone derivatives.Methods: The target compounds were designed and synthesized by inletting different substitution amino groups using acetyl fragment as the connecting segment.Born method was used for preliminary pharmacological test in vitro.Results: Ten target compounds were designed and synthesized; 8 of them were reported firstly and all of them were confirmed by 1HNMR spectra.The results of preliminary pharmacological test showed that all the target compounds exhibited potent antiplatelet aggregation activity.The antiaggregation activities of compounds (6f),(6g),(6h) and (6j) were stong; compounds (6g) and (6j) showed a 5-time higher activity than 6-\[4-(pyridin-4-yl-amino)phenyl\]-4,5-dihydro-3(2H)-pyridazinone (MCI-154).Conclusion: Inletting different substitution amino groups can enhance the antiplatelet aggregation activity of the compounds.