The present invention provides a light source driving circuit and method. The light source driving circuit is used to provide light source driving signals to a light source. The light source driving circuit comprises a light source driving chip, a first pulse width modulation (PWM) signal input terminal, and a first control circuit. The light source driving chip is utilized for generating and outputting the light source driving signals. The first PWM signal input terminal is utilized for receiving a first PWM signal. The first control circuit is utilized for controlling the light source to emit light rays according to the first PWM signal.