Abstract: In order to find new semicarbazide lead compounds, fourteen 4-phenyl-1-pyrazoleformylsem i- bazide were synthesized from 4-chloro-3-ethyl-1-methyl-5-pyrazole form hydrazide and substituted phenylisocyanate. The structures of all new compounds were confirmed by 1 H NMR, IR, MS and elementary analysis. The results of biological tests indicated that 1-( 4-chloro-3-ethy l-1-methyl-1H-pyrazole-5-formyl) -4-(2-methyl-phenyl) semicarbazide ( 4g ) and 1-( 4-chloro-3-ethy l-1-methyl-1H- pyrazole-5-formyl) -4-( 4-chloro-phenyl) semicarbazide ( 4b) showed 90% inhibition rate under the concentration of 500μg /mL against Blumeria graminis and 100% mortality rate to Mythimna separata, respectively.