A light control circuit for use in light control fluorescent lamps comprises a filter and rectifier circuit (1), a frequency control and resonant circuit (2) and an ambient brightness signal sampling and control circuit (4); wherein the ambient brightness signal sampling and control circuit (4) advantageously adopts an integrated circuit (IC2) to control or adjust light sensitivity of the light control circuit in an accurate manner and to control the on/off status of the light control circuit in an intelligent way such that the output of the light control circuit is not susceptible to a sudden change of the ambient brightness.