Abstract: The present disclosure discloses a fill light and a power supply circuit thereof, said power supply circuit is electrically connected to an external power supply device with PD protocol, and comprises a TYPE-C interface module, a PD induction module, a switching tube Q1 as well as a voltage stabilization module, said voltage stabilization module is a Buck-Boost switching power supply module, the input of said voltage stabilization module is connected with the drain of said switching tube Q1. The technical solution uses the PD induction module to disguise the fill light to be presented as an electric equipment for supporting PD protocol, so that the external power supply device with PD protocol can output high voltage above 12V, while using the Buck-Boost switching power module as the voltage stabilization module of this technical solution to improve the adaptability of the power circuit to the input voltage amplitude.