A series of novel aryl pyrazole derivatives containing aminophosphonate were designed and synthesized on the basis of the commercial insecticide Fipronil. Their structures were confirmed by1H NMR, FT-IR, elemental analysis, and compound4 mwas characterized by a single crystal X-ray diffraction analysis. The results of the preliminary bioassays showed that title compounds exhibited satisfactory insecticidal activities againstCulex pipiensandMusca domestica. The introduction of an electron-withdrawing group to the para-position of the benzene ring was essential for high bioactivity. [ABSTRACT FROM AUTHOR]