Phospholipase C (PLC) participates in kinds of hormone-induced signal pathways, however, we know a little about PLC function in ecdysone hormone pathway.In this work, we clone a Phospholipase C gamma 1 (PLC-γ1) gene from Helicoverpa armigera.Semi-quantitative reverse transcription PCR analysis shows that the transcription level of PLC-γ1 reaches its peak at the 5th instar molting stage and the 6th instar prepupal stage, respectively.Hormone injection suggests that PLC-γ1 is up-regulated by 20-hydroxyecdysone (20E).Knockdown of PLC-γ1 by RNA interference in insect cell line restrains the 20E induced gene expression.Knockdown of PLC-γ1 by feeding with Escherichia coli that expressing PLC-γ1 dsRNA suppresses larval development.These data suggest PLC-γ1 regulate insect development via participating 20E signal pathway.