Abstract: Tyrosinase is a key enzyme in the growth and development of insect.The development of insect can be affected by regulating its tyrosinase activity.Eighteen substituted benzylidene hydrazinecarbothioamide (hydrazinecarboxamide,nitrohydrazinecarboximidamide) compounds were designed based on changing the thiourea structure fragment of parent compound benzylidene hydrazinecarbothioamide.The title compounds were synthesized from the starting materials of substituted benzaldehyde,thiosemicarbazide,hydrazine hydrate,etc.in 1 - 2 steps and their structures were characterized by IR,1H NMR and MS (ESI).Their effects on tyrosinase of the diamondback moth Plutella xylostella (L.) were tested.The bioassay results showed that compounds containing thiourea behaved higher inhibitory activity than compounds containing urea (nitro guanidine),which implied that thiourea fragment was favorable to the activity of compounds.