Ten novel benzoyl ureas containing a 1,3,4-thiadiazole group were synthesized by the reaction of 2-amino-5-substituted phenyl-1,3,4-thiadiazole and 2,6-difluorobenzoyl isocyanate，and structurally con-firmed by 1H NMR，IR，ESI-MS techniques and elemental analysis。Preliminary bioassay test indicated that some compounds showed insecticidal activity。Compounds 3d (3,5-(CH3)2) and 3g (4-C4H9) exhibit good insecticidal activity against Aphis craccivora with higer than 90% mortality.

Key words: 1,3,4-thiadiazole, aroyl urea, synthesis, biological activity