A control circuit for LEDs is adapted for controlling brightness of a plurality of LEDs as light source in an LCD. The control circuit comprises a control pulse generator and a plurality of LED direct current supplies. The control pulse generator is used for receiving a brightness adjusting signal and generating a plurality of brightness control pulse signals having the same frequency but different phases according to the brightness control signals. The work cycle of the brightness control pulse signal varies in a predetermined range according to the brightness control signal. The LED direct current provider is coupled to the control pulse generator to drive the corresponding LED according to the brightness pulse signal.