A dimming circuit is disclosed herein. The dimming circuit includes a control voltage receiving module and a driving module. The control voltage receiving module is configured to output a reference voltage according to a control voltage. The driving module is electrically connected to the control voltage receiving module, in which the driving module includes a driving transistor, a first transistor and a feedback circuit. The driving transistor is configured to provide a driving current to drive a lighting module. The first transistor is configured to control the driving transistor with feedback according to the reference voltage. The feedback circuit is electrically connected between the driving transistor and the first transistor and configured to determine the operating state of the first transistor according to the driving current.